Conditional requests for asynchronous wireless communication

ABSTRACT

A wireless media access control supports asynchronous communication and overlapping transmissions. Here, a wireless node may determine whether to request or schedule a transmission based on control messages it receives from neighboring nodes. In some implementations a scheduled transmission may be divided up into several segments so that a transmitting node may receive and transmit control messages between segments. In some implementations a monitoring period is defined after a scheduled transmission period to enable the transmitting node to acquire control information that may otherwise have been transmitted during the scheduled transmission period. In some implementations data and control information are transmitted over different frequency division multiplexed channels to enable concurrent transmission of the data and control information.

CLAIM OF PRIORITY UNDER 35 U.S.C. §119

This application claims the benefit of and priority to commonly ownedU.S. Provisional Patent Application No. 60/836,179, filed Aug. 7, 2006,and assigned Attorney Docket No. 061675P1, the disclosure of which ishereby incorporated by reference herein.

CROSS-REFERENCE TO RELATED APPLICATION

This application is related to concurrently filed and commonly ownedU.S. patent application Ser. No. ______, entitled “TRANSMIT TIMESEGMENTS FOR ASYNCHRONOUS WIRELESS COMMUNICATION,” and assigned AttorneyDocket No. 061675U1; U.S. patent application Ser. No. ______, entitled“CONDITIONAL SCHEDULING FOR ASYNCHRONOUS WIRELESS COMMUNICATION,” andassigned Attorney Docket No. 061675U3; U.S. patent application Ser. No.______, entitled “MONITOR PERIOD FOR ASYNCHRONOUS WIRELESSCOMMUNICATION,” and assigned Attorney Docket No. 061675U4; and U.S.patent application Ser. No. ______, entitled “MESSAGE EXCHANGE SCHEMEFOR ASYNCHRONOUS WIRELESS COMMUNICATION,” and assigned Attorney DocketNo. 061675U5; the disclosure of each of which is hereby incorporated byreference herein.

BACKGROUND

1. Field

This application relates generally to wireless communication, and morespecifically but not exclusively to media access control for anasynchronous wireless system.

2. Background

Various network topologies may be employed to establish wirelesscommunication. For example, a wide area network, a local area network,or some other type of network may be deployed depending on theparticular wireless communication capabilities that are needed for agiven application.

A wireless wide area network is typically a planned deployment within alicensed frequency band. Such a network may be designed to optimizespectral efficiency and quality of service to support a large number ofusers. A cellular network is one example of a wireless wide areanetwork.

A wireless local area network is often deployed without centralizedplanning. For example, such a network may be deployed in an ad hocmanner in unlicensed spectrum. Consequently, this type of network may beused to support a single user or a small number of users. A Wi-Finetwork (i.e., an IEEE 802.11-based network) is one example of awireless local area network.

In practice, each of the above networks has various disadvantages due totradeoffs that may be made to provide a given type of service. Forexample, due to the complexity of centralized planning, setting up awireless wide area network may be relatively expensive and timeconsuming. Hence, such a scheme may not be well suited for “hot spot”deployments. On the other hand, an adhoc network such as Wi-Fi may notachieve the same level of spatial efficiency (bits/unit area) as aplanned network. Moreover, to compensate for potential interferencebetween nodes in the network, a Wi-Fi network may employ interferencemitigation techniques such as carrier sense multiple access. Suchinterference mitigation techniques may, however, lead to poorutilization and provide limited fairness control, and may be susceptibleto hidden and exposed nodes.

SUMMARY

A summary of sample aspects of the disclosure follows. It should beunderstood that any reference to aspects herein may refer to one or moreaspects of the disclosure.

The disclosure relates in some aspects to wireless media access controlthat supports asynchronous communication. Here, different sets of nodes(e.g., a transmitting node and a receiving node that are associated tocommunicate with one another) may communicate in an asynchronous mannerwith respect to other sets of nodes. Thus, the timing and duration of atransmission for a given set of nodes may be defined independently ofthe timing and duration of a transmission for a different set of nodes.

The disclosure also relates in some aspects to wireless media accesscontrol that supports overlapping wireless transmissions. Here, a set ofnodes may schedule a transmission based on consideration of a current orfuture transmission by one or more neighboring nodes. This considerationmay involve, for example, defining appropriate transmission parameterssuch as transmission rate, code rate, and transmission time to ensurethat the transmission will not unduly interfere with other nodes andwill be reliably received at the associated receiving node.

In some aspects a node analyzes control messages transmitted by anothernode to determine whether to request or schedule a transmission. Forexample, a first node may transmit a control message (e.g., a grant orconfirmation) that indicates the time of a scheduled transmission aswell as the relative transmission power of the first node. A second nodethat receives this control message may thereby determine, based on thepower level of the received message and the rate and duration of thescheduled transmission, whether and to what extent transmission by thesecond node would affect or reception at the second node would beaffected by the scheduled transmission of the first node. For example, atransmitting node may determine whether to initiate a request totransmit to a receiving node based on whether the desired transmissionwill interfere with reception at a node that is near the transmittingnode. Similarly, a receiving node may determine whether to issue a grantmessage to schedule the requested transmission based on whether thetransmission in question may be reliably received in view of anyscheduled transmissions by one or more nodes that are near the receivingnode.

In some aspects a scheduled transmission may be divided up into severalsegments where a time period is defined between each segment for thereception and transmission of control messages. In the event thecondition of the transmission channel or interference condition haschanged in some way, the transmitting node may thus receive controlinformation indicative of this so that the transmitting node may adaptone or more transmission parameters for the subsequent segments. Inaddition, in the event there is no need to transmit data during one ormore previously scheduled segments, the transmitting node may receivecontrol information indicating that the current transmission opportunitymay end. Also at this time, the transmitting node may transmit controlinformation to neighboring nodes to keep them informed as to whetherthere will be any subsequent segments and, if so, the transmissionparameters to be used for the subsequent segments.

In some aspects a monitoring period is defined after a scheduledtransmission period to enable the transmitting node to acquire controlinformation that may otherwise have been transmitted during thescheduled transmission period. For example, a neighboring node may delaytransmission of a control message until after the end of the scheduledtransmission period to ensure that the transmitting node receives themessage. This stems from the fact that a node that is transmitting dataon the data channel may not be capable of simultaneously receiving dataeither on the data or control channel, in a Time Division Duplex (“TDD”)system. Alternatively, a neighboring node may transmit a control messageafter the end of the scheduled transmission period whereby the controlmessage including information that was previously transmitted during thescheduled transmission period.

In some aspects data and control information are transmitted overdifferent frequency division multiplexed (“FDM”) channels to enableconcurrent transmission of the data and control information. In someimplementations the data and control channels are associated with acontiguous frequency band whereby portions of the control channel areinterspersed between portions of the data channel within the commonfrequency band. In this way, frequency diversity and rate prediction ofthe system may be improved.

BRIEF DESCRIPTION OF THE DRAWINGS

Sample features, aspects and advantages of the disclosure will bedescribed in the detailed description and appended claims that follow,and in the accompanying drawings, wherein:

FIG. 1 is a simplified block diagram of several sample aspects of acommunication system;

FIG. 2 is a flowchart of several sample aspects of communicationoperations that may be performed by nodes in an asynchronous wirelesssystem;

FIG. 3 is a simplified diagram of several sample aspects of frequencydivision multiplexed channels;

FIG. 4 is a simplified timing diagram of several sample aspects of amessage exchange scheme;

FIG. 5 is a simplified block diagram of several sample aspects of atransmitting node;

FIG. 6 is a simplified block diagram of several sample aspects of areceiving node;

FIG. 7, including FIGS. 7A and 7B, is a flowchart of several sampleaspects of operations that may be performed by a transmitting node;

FIG. 8, including FIGS. 8A and 8B, is a flowchart of several sampleaspects of operations that may be performed by a receiving node;

FIG. 9, including FIGS. 9A and 9B, are flowcharts of several sampleaspects of operations that may be performed in conjunction with aresource utilization message-based fairness scheme;

FIG. 10 is a flowchart of several sample aspects of operations that maybe performed in conjunction with determining whether to transmit over acontrol channel;

FIG. 11 is a simplified timing diagram of several sample aspects of amessage exchange scheme illustrating an example where nodes transmit atdifferent times;

FIG. 12 is a simplified timing diagram of several sample aspects of amessage exchange scheme illustrating an example where nodes transmit atthe same time;

FIG. 13, including FIGS. 13A and 13B, are flowcharts of several sampleaspects of operations that may be performed in conjunction withscheduling transmission of control information;

FIG. 14 is a simplified block diagram of several sample aspects ofcommunication components; and

FIGS. 15-19 are several simplified block diagrams of several sampleaspects of apparatuses configured to support asynchronous wirelesscommunication.

In accordance with common practice the various features illustrated inthe drawings may not be drawn to scale. Accordingly, the dimensions ofthe various features may be arbitrarily expanded or reduced for clarity.In addition, some of the drawings may be simplified for clarity. Thus,the drawings may not depict all of the components of a given apparatus(e.g., device) or method. Finally, like reference numerals may be usedto denote like features throughout the specification and figures.

DETAILED DESCRIPTION

Various aspects of the disclosure are described below. It should beapparent that the teachings herein may be embodied in a wide variety offorms and that any specific structure, function, or both being disclosedherein is merely representative. Based on the teachings herein oneskilled in the art should appreciate that an aspect disclosed herein maybe implemented independently of any other aspects and that two or moreof these aspects may be combined in various ways. For example, anapparatus may be implemented or a method may be practiced using anynumber of the aspects set forth herein. In addition, such an apparatusmay be implemented or such a method may be practiced using otherstructure, functionality, or structure and functionality in addition toor other than one or more of the aspects set forth herein. For example,in some aspects a transmitting node determines whether to issue arequest to transmit based on information the node has received regardingscheduled receptions of neighboring nodes. In addition, in some aspectsa receiving node determines whether to schedule a transmission based oninformation that node has received regarding scheduled transmissions ofits neighboring nodes.

FIG. 1 illustrates several sample aspects of a wireless communicationsystem 100. The system 100 includes several wireless nodes, generallydesignated as nodes 102 and 104. A given node may receive one or moretraffic flows, transmit one or more traffic flows, or both. For example,each node may comprise at least one antenna and associated receiver andtransmitter components. In the discussion that follows the termreceiving node may be used to refer to a node that is receiving and theterm transmitting node may be used to refer to a node that istransmitting. Such a reference does not imply that the node is incapableof performing both transmit and receive operations.

In some implementations a node may comprise an access terminal, a relaypoint, or an access point. For example, the nodes 102 may compriseaccess points or relay points and the nodes 104 may comprise accessterminals. In a typical implementation the access points 102 provideconnectivity for a network (e.g., a Wi-Fi network, a cellular network, aWiMax network, a wide area network such as the Internet, and so on). Arelay point 102 may provide connectivity to another relay point or to anaccess point. For example, when an access terminal (e.g., accessterminal 104A) is within a coverage area of a relay point (e.g., relaypoint 102A) or an access point (e.g., access point 102B), the accessterminal 104A may be able to communicate with another device connectedto the system 100 or some other network.

In some aspects different sets of nodes in the system 100 maycommunicate in an asynchronous manner with respect to other sets ofnodes. For example, each set of associated nodes (e.g., a set includingnodes 104A and 104B) may independently select when and for how long oneof the nodes in the set will transmit data to the other node in the set.In such a system, various techniques may be deployed to reduceinterference between nodes and ensure that access to the communicationmedium is provided to all of the nodes in a fair manner, while utilizingthe available bandwidth of the communication medium to the greatestpractical extent.

The discussion that follows describes various media access control andrelated techniques that may be employed to, for example, reduceinterference, facilitate fair sharing of resources, and achieverelatively high spectral efficiency. Referring initially to FIG. 2, thisfigure sets forth an overview of operations that may be performed bywireless nodes to determine whether and how to transmit at the same timeand on the same channel as neighboring wireless nodes.

In some aspects wireless nodes may communicate through the use ofseparate control and data channels. In addition, in some implementationsthe control channel may be used to transmit relatively short controlmessages. In this way, the control channel may be lightly utilizedwhich, in turn, may reduce delays on the control channel and reducecollisions on that channel if it supports random access.

As represented by block 202, in some aspects wireless nodes maycommunicate via frequency division multiplexed control and datachannels. Through the use of frequency separated channels, differentsets of wireless nodes may simultaneously transmit and receive data andcontrol information thereby improving the utilization of the datachannel. For example, at the same time the data channel is being used totransmit data from a first wireless node to a second wireless node,other wireless nodes that are not involved in this data exchange mayexchange control information on the control channel to setup the datachannel either in an overlapping manner with the current data exchangeor at the completion of it. Thus, the other wireless nodes do not needto wait until the end of the current data transmission to contend forthe data channel.

FIG. 3 illustrates in a simplified manner an example of how a datachannel and a control channel may be frequency division multiplexed. Inthis example a control channel 304 as represented by sub-channels304A-304D and a data channel as represented by sub-channels 306A-306Dare contiguously defined within a common frequency band 302. Here, thefrequency band 302 is defined as a range of frequencies from a lowerfrequency of f₁ to a higher frequency of f₂. It should be appreciated,however, that the common frequency band 302 may be defined in some othermanner (e.g., substantially contiguous or not contiguous).

In FIG. 3 the control channel 304 is tone-interleaved with the datachannel 306. In other words, the control channel is associated with aplurality of sub-frequency bands that are interspersed within the commonfrequency band 302. The use of such a tone-interleaved control channelmay provide frequency diversity and improved rate prediction. Forexample, in accordance with some aspects of the disclosure controlchannel RSSI measurements may be used for signal and interferenceestimation and to predict appropriate rates for transmission over thedata channel. Consequently, by interspersing portions of the controlchannel throughout the data channel these measurements may moreaccurately reflect the conditions throughout the data channel. Giventhat more accurate interference estimation may be made in this way, thesystem may be able to better select an acceptable transmission andcoding rate for any data transmissions that are subject to thisinterference.

It should be appreciated that one or more control channels and one ormore data channels may be defined in the above manner. For example, thesub-channels 304A-304D may represent a single control channel ormultiple control channels. Similarly, the sub-channels 306A-306D mayrepresent a single data channel or multiple data channels.

FIG. 3 also illustrates that in some implementations frequency guardbands 308 may be defined between adjacent control and data sub-channels.In other words, subsets of the frequency band 302 between thesub-channels may be assigned to neither the data channel nor the controlchannel. In this way, interference between adjacent data and controlsub-channels may be reduced to some extent to alleviate, for example,near-far problems.

It should be appreciated that the above describes but one example of howwireless nodes may communicate. Thus, in other implementations data andcontrol information may be transmitted on a common channel or in someother manner. For example, the data and control channel may be timedivision multiplexed rather than frequency division multiplexed.

In addition, other forms of multiplexing may be employed for the controlchannel. For example if there are several OFDM symbols in time, thecontrol channel could frequency hop from symbol to symbol to effectivelyachieve the same effect as the example of FIG. 3. This scheme may beemployed as an alternative to utilizing only a few select frequenciesover all OFDM symbols (e.g., the four bands depicted in FIG. 3).

Referring again to FIG. 2, as represented by block 204 nodes may monitora communication medium for control information from one or more othernodes to support interference management and fairness. Here, it may beassumed that any transmitting node that does not receive a controlmessage from another node (e.g., due to the distance between the nodes)will not interfere with the node that sent the control message.Conversely, any node that does receive a control message is expected totake appropriate measures to ensure that it does not interfere with thenode that sent the control message.

For example, each node in the system may transmit control informationthat provides certain details regarding its scheduled (e.g., current orupcoming) transmissions. Any nearby nodes that receive this controlinformation may thus analyze the information to determine whether theymay overlap their data transmission, either fully or partially, with thescheduled transmission(s) without unduly interfering with the scheduledtransmissions. Fairness may be achieved through the use of resourceutilization messages that indicate whether a given receiving node is notreceiving data at an expected level of quality of service. Here, anytransmitting node that receives the resource utilization messages maylimit its transmission to improve the reception at the disadvantagedreceiving node.

FIG. 4 is a simplified timing diagram that illustrates an example ofreceipt and transmission of information (e.g., messages) at a pair ofassociated wireless nodes A and B. The upper waveform 402 representscontrol channel information transmitted and received by node A. Themiddle waveform 404 represents control channel information transmittedand received by node B. The lower waveform 406 represents transmissionof data from node A to node B via a data channel. For the respectivecontrol channels, transmission of information is represented by a blockabove the horizontal line (e.g., block 408) while reception ofinformation is represented by a block below the horizontal line (e.g.,block 410). In addition, the dashed boxes represent the correspondingreception at one node of information transmitted by the other node.

In some implementations, a pair of associated nodes may employ arequest-grant-confirmation scheme to manage interference and maximizesystem resource reuse. Briefly, a node (i.e., a transmitting node) thatwishes to send data to another node (i.e., a receiving node) initiatesthe exchange by transmitting a request to transmit. An associatedreceiving node may then schedule the transmission by granting therequest, whereby the grant may also define when and how the transmissionwill take place. The transmitting node acknowledges receipt of the grantby transmitting a confirmation.

In some implementations, the grant and confirmation may includeinformation that describes one or more parameters of the scheduledtransmission. For example, this information may indicate when thetransmission will occur, transmission power to be used for thetransmission, and other parameters that will be discussed below. A nodemay thereby monitor the control channel to regularly acquire thisinformation from its neighboring node and use the acquired informationto determine whether or how to schedule its own transmissions(corresponding to receptions for a receiving node).

FIG. 4 illustrates an example where node A has observed a series ofgrants from nodes in its vicinity over a period of time and where node Bhas observed a series of confirmations from nodes in its vicinity over aperiod of time as represented by the line 412. Note that these observedgrants (414 A-C) and confirmations (416 A-C) on the control channel areunrelated to any transmissions or receptions by either Node A or Node B.Here the grants are represented by grant blocks (“G”) 414A-414C and theconfirmations are represented by confirmation blocks (“C”) 416A-416C. Itshould be appreciated that the nodes may receive other types of controlmessages during time period 412. However, the receipt of grants by atransmitting node (e.g., node A) and the receipt of confirmations (e.g.,node B) by receiving node are the primary focus of the discussion thatimmediately follows regarding the operation of block 204.

In some aspects, node A generates a transmit constraints state based onthe received grants. For example, the transmit constraints state maycomprise records of the information provided by each of the grants. Inthis way, node A will have information relating to the transmissionsthat have been scheduled by any receiving nodes that are close to nodeA. Thus, the transmit constraints state provides a mechanism wherebynode A may determine whether any of the receiving nodes with which nodeA may potentially interfere are currently receiving data or will bereceiving data.

In a similar manner, node B generates a rate prediction state based onthe received confirmations. In some implementations the rate predictionstate may comprise records of the information provided by each of theconfirmations. Thus, node B will have information relating to scheduledtransmissions of any transmitting nodes that are close to node B. Inthis way, the rate prediction state provides a mechanism whereby node Bmay determine whether any transmitting nodes that may interfere at nodeB are currently transmitting data or will be transmitting data.

Here, it should be appreciated that node B's neighboring nodes may bedifferent than node A's neighboring nodes. For example, where thedefinition of a neighboring node is based on whether a node may receivecontrol messages from another node, if nodes A and B are separated by afair distance, some of the nodes that may communicate with node B maynot be able to communicate with node A and vice versa. Consequently,nodes A and B may independently identify their neighboring nodes inconjunction with the interference avoidance and fairness operationsdescribed herein.

Referring again to the flowchart of FIG. 2, a samplerequest-grant-confirmation message exchange will be described. At block206, a transmitting node that wishes to transmit data to a receivingnode may send a request to transmit. Here, a decision by thetransmitting node as to whether to issue a request may be based on itstransmit constraints state (e.g., based on received controlinformation). For example, node A may determine whether its scheduledtransmission will interfere with any scheduled receptions at receivingnodes that are near node A. As will be discussed in more detail below,based on this determination node A may decide to proceed with itstransmission, postpone its transmission, or alter one or more parametersassociated with its transmission.

If the transmitting node determines that the transmission may bescheduled it transmits the request message to the receiving node. In theexample of FIG. 4, this is represented by the request block (“R”) 408.

As represented by block 208, upon receipt of the request the associatedreceiving node determines whether to schedule the requestedtransmission. Here, the receiving node's determination of whether toschedule the requested transmission may be based on its rate predictionstate (e.g., based on received control information). For example, node Bmay determine whether it will be able to reliably receive the requestedtransmission in view of any scheduled transmissions by transmittingnodes that are near node B. As will be discussed in more detail below,based on this determination node B may decide to schedule the requestedtransmission, not schedule the requested transmission, or adjust one ormore parameters (e.g., transmit timing, transmit power, transmit rate,code rate) associated with the requested transmission to enablesustainable reception of the transmission.

If the receiving node elects to schedule the transmission, it transmitsa grant back to the transmitting node. In the example of FIG. 4, thegrant block (“G”) 418 represents the transmission and reception of thegrant message by node B and node A, respectively. As mentioned above,the grant may include information relating to the scheduledtransmission. Consequently, any transmitting node that receives thegrant 418 may define (e.g., update or create) its transmit constraintsstate based on this information.

As represented by block 210 of FIG. 2, upon receipt of a grant messagefrom an associated node, a transmitting node broadcasts a confirmationmessage to confirm the grant by its associated receiving node and toinform its neighboring nodes of the scheduled transmission. In theexample of FIG. 4, the confirmation block (“C”) 420 represents thetransmission and reception of the grant message by node A and node B,respectively. As mentioned above the confirmation may includeinformation relating to the scheduled transmission. Consequently, anyreceiving node that receives the confirmation 420 may define (e.g.,update or create) its rate prediction state based on this information.

As represented by block 212, following transmission of the confirmationa transmitting mode transmits its data during the scheduled transmissiontime period as represented by a transmission opportunity (“TXOP”)interval 422 in FIG. 4. In some implementations, a single transmissionopportunity (e.g., that is associated with a relatively long TXOPperiod) may be broken up into smaller segments to allow betterinterference management and rate selection for ongoing transmissions. Inthe example of FIG. 4 the scheduled transmission is defined as a seriesof transmit time segments 424A and 424B that are separated by a timeinterval 426 that is designated for receiving or transmitting controlinformation. For example, node A may transmit data during time segment424A, then monitor for control messages and/or transmit control messagesduring the time interval 426, then transmit data again during timesegment 424B. It should be appreciated that the relative lengths of thetime periods in FIG. 4 are not necessarily the same as those that may beused in an actual system.

By subdividing the transmission in this way, node A may adapt itstransmission of data during subsequent time segments (e.g., time segment424B) if it is determined that conditions on the communication mediumhave changed from the time of the initial grant 418. For example, duringthe time segment 424A, node B may receive additional control information(e.g., confirmation 416D) from one of its neighboring nodes. Based onthis information (e.g., indicating a scheduled transmission during timesegment 424B), node B may adapt its rate prediction state. In the eventany change in the rate prediction state relates to channel conditionsduring the time segment 424B, node B may adapt the transmissionparameters (e.g., transmission rate, number of redundancy bits toinclude and so on) for subsequent transmissions by node A.

In some implementations a receiving node may transmit transmissionparameters such as these to its associated transmitting node inconjunction with an acknowledgement of a given transmission segment. Inthe example of FIG. 4, node B transmits an acknowledgement 428 to node Ato acknowledge receipt of the segment 424A. The acknowledgement 428 alsomay include or be transmitted in conjunction with information that issimilar to the information transmitted in the grant 418. Thus, thisinformation may define or relate to a transmission time period, transmitpower information, and other information to be used by node A fortransmission of the subsequent segments (e.g., segment 424B). Theacknowledgement 428 also may be used to provide this information totransmitting nodes that are close to node B so that these nodes mayupdate their respective transmit constraints states.

In some implementations node A may monitor for control information fromother nodes during the interval 426. For example, node A may receivegrants or resource utilization messages whereby node A may elect toadjust its current transmission or a subsequent transmission based onthe received information.

In some implementations node A may transmit a confirmation 430 duringthe interval 426. The confirmation 430 may include, for example,information similar to the information provided by the confirmation 420.Thus, the confirmation 430 may define or relate to a transmission timeperiod, transmit power information, and other information to be used bynode A for transmission of the subsequent segments (e.g., segment 424B).In some cases the confirmation 430 may be generated in response to theacknowledgement 428. In particular, in the event the acknowledgement 428called for adaptation of the transmission parameters for subsequent timesegments, the confirmation 430 may be used to provide this informationto the receiving nodes that are close to node A so that these nodes mayupdate their respective rate prediction states.

Referring again to FIG. 2, as represented by block 214 in someimplementations after the transmitting node completes its transmissionit may monitor the control channel for a defined period of time. Forexample, as represented by the post-TXOP monitor period 432 of FIG. 4,this period of time may immediately (or substantially immediately)follow the TXOP period 422. Through the use of this monitor period, anode may define (e.g., update or reacquire) its transmit constraintsstate and rate prediction state information to enable the node tosubsequently initiate requests to transmit data and to generate grantsthat schedule the reception of data at the node. Here, it should beappreciated that the node may not have received control messages duringthe time periods the node was transmitting (e.g., time segment 424A andtime segment 424B). For example, node A would not have received thegrant 410 and a confirmation 434 that may have been transmitted by areceiving node and a transmitting node, respectively, that are close tonode A. Accordingly, in some implementations these neighboring nodes maybe configured to transmit this information during the post-TXOP period432 so that node A may define its states based on this information.

In some implementations a node may be configured to delay transmissionof its control information to ensure that its neighboring nodes (e.g.,node A) receive this information. Here, the node may monitor the controlinformation transmitted by its neighbors (e.g., the confirmation 420from node A) to determine when those nodes will be transmitting. Thenode may then delay transmission of its control information until afterthe completion of its neighbor's transmit time period (e.g., time period422). This is illustrated in FIG. 4, for example, by a grant 436 and aconfirmation 438 that are received by node A during the post-TXOP period432.

In some implementations a node may be configured to retransmit itscontrol information to ensure that its neighboring nodes (e.g., node A)receive this information. In this case, the node may initially transmitits control information (e.g., the grant 410 or the confirmation 434) ata normal time (e.g., not delayed). However, the node also may monitorthe control information transmitted by its neighbors (e.g., node A) todetermine whether any of those nodes will be or were transmitting whenthe node transmits its control information. If so, the node may transmitadditional control information that repeats information that waspreviously transmitted. In this case the grant 436 and the confirmation438 that are received by node A during the post-TXOP period 432 maycorresponding to “retransmitted” control information.

In some implementations the length of the post-TXOP period 432 isdefined to be at least as long as the maximum length of a time segment(e.g., time segment 424A) plus the maximum length of the interval 426 inthe wireless communication system. In this way, a node that ismonitoring the control channel during the period 432 may be assured ofreceiving any acknowledgements or confirmations transmitted during theinterval 426 defined for any other set of associated nodes in thesystem. In addition, a disadvantaged receiving node may use the period432 to broadcast a resource utilization message (“RUM”) or transmit adirected RUM to a specific node (e.g., a node associated with TXOPs thatare causing unfairness to the receiving node) in an attempt to improvethe quality of service at the disadvantaged receiving node. As will bediscussed in more detail below, a RUM provides a mechanism whereby anode may make its neighbors back-off their transmissions, therebyenabling the node to gain access to the channel in an expedient manner.Various details regarding several sample implementations andapplications of RUMs are discussed in United States Patent ApplicationPublication No. 2007/0105574, the disclosure of which is herebyincorporated by reference herein.

With the above description in mind, several examples of additionalimplementation and operational details that may be employed based on theteachings herein will be discussed in conjunction with FIGS. 5-8. FIG. 5illustrates several sample functional components associated with atransmitting node 500 (e.g., a wireless node performing transmitoperations). FIG. 6 illustrates several sample functional components ofa receiving node 600 (e.g., a wireless node performing receiveoperations). FIG. 7 illustrates several sample operations that may beperformed by a transmitting node. FIG. 8 illustrates several sampleoperations that may be performed by a receiving node.

Referring initially to FIGS. 5 and 6, the transmitting and receivingnodes 500 and 600 include various components for communicating with oneanother or other wireless nodes. For example, the nodes 500 and 600include transceivers 502 and 602, respectively, for transmittinginformation (e.g., data and control information) and receivinginformation via a wireless medium. In addition, the nodes 500 and 600respectively include control message generators 506 and 606 forgenerating control messages and control message processors 504 and 604for processing received control messages. Channel definers 508 and 608may cooperate to define, select, or otherwise implement the data andcontrol channels used by the nodes 500 and 600 to communicate with oneanother or some other node. For example, channel definers 508 and 608may cooperate with the transceivers 502 and 602, respectively, so thatdata and control information are transmitted and received viaappropriate frequency bands (e.g., as illustrated in FIG. 3). The nodes500 and 600 also include respective data memories for storing, forexample, transmission parameters 510 and 610 and state records 512 and612, respectively. In addition, the transmitting node 500 includes atransmission controller 514 for controlling various transmission-relatedoperations of the node 500 and the receiving node 600 includes areception controller 614 for controlling various reception-relatedoperations of the node 600. The receiving node 600 also includes aresource utilization message (“RUM”) generator 616 for generatingresource utilization messages while the transmitting node 500 includes aRUM processor 532 for processing received RUMs.

Sample operations of the transmitting node 500 and the receiving node600 will be discussed in more detail in conjunction with the flowchartsof FIGS. 7 and 8, respectively. For convenience, the operations of FIGS.7 and 8 (or any other operations discussed or taught herein) may bedescribed as being performed by specific components (e.g., components ofthe nodes 500 or 600). It should be appreciated, however, that theseoperations may be performed by other types of components and may beperformed using a different number of components. It also should beappreciated that one or more of the operations described herein may notbe employed in a given implementation.

As represented by blocks 702 and 802 the nodes 500 and 600 monitor thecontrol channel for control messages on a regular basis. For example, ina typical configuration a receiver 518 of node 500 and a receiver 618 ofnode 600 will each monitor the control channel whenever thecorresponding transmitter 520 and 620 of each node is not transmitting.In other words, a node may acquire control messages when it is receivingor is idle. In this way, each of the nodes 500 and 600 may acquirecontrol information relating to scheduled transmissions associated withneighboring nodes, and thereby maintain state as discussed below.

The control message processors 504 and 604 of each node process eachreceived control message and extract the transmission schedule and otherinformation from the message. As discussed above, a received controlmessage may comprise a grant, a confirmation, an acknowledgement, orsome other suitable control information. Here, for a node that wishes totransmit (i.e., a transmitting node), grants and acknowledgementsgenerated by neighboring receiving nodes are of particular interestsince the transmitting node will use the information provided by thesecontrol messages to determine whether it will interfere with scheduledreceptions of its neighbors. Conversely, for a node that wishes toreceive (i.e., a receiving node), confirmations generated by neighboringtransmitting nodes are of particular interest since the receiving nodewill use the information provided by these control messages to determinewhether it may receive data on a sustainable basis in view of scheduledtransmissions by these nodes.

As mentioned above, a grant or an acknowledgement may includeinformation relating to a granted resource and the timing and durationof the corresponding granted TXOP. These timing parameters may include,for example, the start time for the TXOP, the end time for the TXOP, andthe duration of the TXOP. In some implementations these timingparameters may be relative to the transmission time of the message or tosome other timing reference.

A grant or acknowledgement also may include transmission parameters thatwere defined at the receiving node to facilitate reliable reception of atransmission at the receiving node. As mentioned above, the receivingnode may define these parameters based on scheduled (e.g., ongoing orfuture) transmissions by nodes that are in the vicinity of the receivingnode. This information may include, for example, recommended ordesignated transmission parameters such as transmit power, transmissionrate, a quantity of redundancy bits to transmit, and code rate to beused by an associated transmitting node during the scheduledtransmission.

In some implementations a grant or acknowledgement may indicate achannel-to-interference ratio (“C/I”) expected at the receiving node. Inthis case, an associated transmitting node may use this information todefine appropriate transmission parameters.

In some implementations a grant or acknowledgement may indicate thereceive margin at the receiving node. This receive margin may indicate,for example, how much margin (e.g., defined in decibels) is built intothe transmission parameters provided by the control message.Consequently, a transmitting node may use the receive margin informationto ensure that any interference caused by its overlapping transmissionswill be low enough such that an error correction mechanism (e.g., HARQ)at the receiving node will be able to recover the associated packet.

In some implementations a grant or acknowledgement may comprise or beassociated with a pilot signal that a neighboring node may use todetermine to what extent a specific transmit power value will affect(e.g., interfere with) the receiving node. For example, the pilot signalmay be associated with a fixed and known power spectral density ortransmit power whereby the transmitting node may use this knowninformation to determine the path loss to the neighboring receivingnode. To this end, the receiver 518 may include a received signalstrength indication (“RSSI”) measurer 524 that may be used to measurethe signal strength of the received signal (e.g., pilot). In someimplementations, this pilot signal may be sent over one or more of thecontrol sub-channels, so that a sample of the entire channel can bereliably obtained (e.g. for advantage in a channel with frequencyselective fading).

In some implementations a confirmation may include information that issimilar to the information described above in conjunction with the grantand acknowledgement, except that in this case the information is from aneighboring node that will be transmitting during the scheduledtransmission period. For example, a confirmation may include the starttime for the TXOP, the end time for the TXOP, the duration of the TXOP,transmit power, transmission rate, a quantity of redundancy bits totransmit, and code rate.

A confirmation may also comprise or be associated with a pilot signal.Again, the pilot signal may be associated with a fixed and known powerspectral density or transmit power whereby a receiving node maydetermine the path loss to the transmitting node. Thus, the receiver 618also may include an RSSI measurer 624 that may be used to measure thesignal strength of a received confirmation signal (e.g., pilot).

In some implementations a confirmation may indicate the transmit powerdelta to be used by the transmitting node for its scheduledtransmission. This power delta may indicate, for example, the difference(e.g., increase or decrease) between the power level of a message to betransmitted during the scheduled transmission and the power level of theconfirmation (e.g., the associated pilot signal). Through the use of thetransmit power delta and the measured power level of the receivedconfirmation, a receiving node may determine how much interference itcan expect from the neighboring transmitting node. For example, based onthe received confirmations for previously scheduled transmissions, thereceiving node may construct a profile (e.g., state records) of receivedinterference level versus time.

As represented by blocks 704 and 804, state controllers 522 and 622define the state records for each node based on the received controlinformation. Here, as new control information is received, it is addedto the appropriate state record. Conversely, upon completion of a givenTXOP (e.g., as indicated by comparing the end time of the TXOP with thecurrent time), the associated record is removed from the state record.

The transmit constraint state records 512 are shown in FIG. 5 sincethese records are of particular interest for the transmitting node 500.As mentioned above, the transmit constraint state includes records ofreceived grants and in some implementations received acknowledgements.Thus, an entry 526 of the state records 512 for a given received messagemay include the start time of a scheduled transmission (or the currenttime if the transmission is in progress), the corresponding end time, atransmission time period, receive margin, the RSSI associated with thereceived message, C/I, and the receive margin of the node thattransmitted the message (e.g., a node that sent the grant oracknowledgement).

The rate prediction state records 612 are shown in FIG. 6 since theserecords are of particular interest for the receiving node 600. The rateprediction state includes records of received confirmations. Thus, anentry 626 of the state records 612 for a given received message mayinclude the start time of a scheduled transmission (or the current timeif the transmission is in progress), the corresponding end time, atransmission time period, the RSSI associated with the received message,and the transmit power delta of the node that transmitted the message.

Referring now to blocks 806 and 706 of FIGS. 8 and 7, in someimplementations the nodes in a system may implement a resourceutilization message (“RUM”) scheme in an attempt to ensure that theresources of the system are shared between nodes in a fair manner. Ingeneral, the operation of block 806 involves transmitting messages overthe control channel to indicate that the receiving node is disadvantaged(e.g., due to interference the node “sees” while receiving) and that thenode desires priority access to the shared communication medium (e.g., agiven data channel). At block 706 of FIG. 7, the transmitting nodemonitors the incoming traffic on the control channel to determinewhether any of its neighboring nodes have transmitted a RUM. Thisinformation is then taken into account whenever the transmitting nodewishes to invoke a request to transmit. Sample operations relating to aRUM-based scheme will be treated in more detail in conjunction with FIG.9.

As represented by block 902 in FIG. 9A, at some point in time (e.g., ona regular basis) the receiving node determines whether it is receivingdata in accordance with an expected quality of service level (e.g., anexpected data rate or latency). In some cases the quality of service maybe lower than expected due to interference from neighboring transmittingnodes. For example, the receiving node may be unable to grant a requestto transmit from associated transmitting node due to the scheduledtransmissions of the neighboring nodes. In the event the receiving nodedetermines that it is disadvantaged, it may generate a RUM in an attemptto cause neighboring nodes to interfere less. The response by theneighboring nodes may be in terms of contending less for transmission onthe data channel for a period of time by requesting less frequently orlowering power or other suitable means to satisfy the RUM-sending node.

As represented by block 904, in some implementations, a RUM may beweighted (e.g., include a weight value) to indicate the degree to whichreception at a receiving wireless node is not meeting a desired level ofquality of service (e.g., the degree to which the receiving node isdisadvantaged). For example, the disadvantaged receiving node maycalculate a RUM weight value that indicates the degree to which theexpected receive data rate differs from the actual receive data rate(e.g., a ratio of the two values).

As represented by block 906, in practice a RUM may include various typesof information. For example, in some implementations a RUM may designatea level of desired interference reduction. In addition, in someimplementations a RUM may indicate a particular resource that thedisadvantaged receiving node wishes to be cleared.

As represented by block 908, the receiving node then transmits the RUMvia the control channel. In the example of FIG. 6, the RUM generator 616may generate the above RUM-related information. The control messagegenerator 606 may then cooperate with the transmitter 620 to transmitthe RUM over the control channel.

As represented by block 708 in FIG. 7, the transmitting node determineswhether or how to issue a request to transmit based on the transmitconstraints state and, optionally, any received RUMs. In some aspectsthe request indicates that the transmitting node has data to betransmitted to its associated receiving node (or nodes). In addition,the request may serve to indicate there are no ongoing transmissionsthat prevent the transmitting node from transmitting the data.

If it was determined at block 706 that a neighboring node hastransmitted a RUM, the transmitting node may utilize the receipt of theRUM, the weight thereof, and any other information included in the RUMto determine an appropriate response. For example, the transmitting nodemay limit its future transmissions or it may ignore the RUM if, forinstance, the node has received a RUM from an associated receiving nodethat indicates that the associated receiving node is more disadvantagedthan any other neighboring receiving node.

Referring to FIG. 9B, at block 910 the RUM processor 532 of thetransmitting node 500 determines whether a received RUM indicates that aneighboring receiving node is more disadvantaged than the receiving nodeassociated with the transmitting node. As a preliminary measure, atblock 912 an interference determiner 528 may determine whether thetransmitting node's transmission would even interfere with thedisadvantaged receiving node (e.g., as discussed above). This mayinvolve, for example, comparing receive power information (e.g., RSSI ofa pilot signal) associated with a received RUM with an appropriatethreshold level. If it is determined that the transmit power to be usedduring the transmission is sufficiently low or that other parameters ofthe desired transmission (e.g., transmit times) would not lead to undueinterference at the disadvantaged receiving node, the transmitting nodemay ignore the received RUM.

At block 914, in the event the transmitting node determines that thedesired transmission may interfere with reception at the disadvantagedreceiving node, the transmitting node 500 may take appropriate action(e.g., define different transmission parameters) to avoid suchinterference. For example, the transmitting node 500 (e.g., thetransmission controller 514) may perform one or more of: delay sendingof a request to transmit, abstain from transmitting request messagesuntil a resource utilization message of an associated receiving nodeindicates a higher degree of disadvantage than the received resourceutilization message, send a request that requests to transmit at a latertime, change (e.g., decrease) a rate at which the node transmits requestmessages, change (e.g., decrease) a length of a transmit time period(e.g., TXOP), send a request to transmit at a different (e.g., reduced)power level, change (e.g., reduce) a transmit power delta, modify a setof rules (e.g., one or more rules 530) relating to a degree to whichtransmission by a node may interfere with reception at a neighboringnode (e.g., change a margin of safety), or perform some other suitableaction.

The transmitting node may perform reciprocal operations when thereceived RUMs indicate that the receiving node associated with thetransmitting node is more disadvantaged than other nodes. For example,in this case the transmitting node may increase the rate at which ittransmits requests, increase the length of its TXOP, and so on.

As mentioned above, a transmitting node also may limit a request basedon the current state. In the example of FIG. 5, the interferencedeterminer 528 may use the transmit constraints state records 512 todetermine whether a desired transmission will interfere with anyscheduled reception of data at nodes that are relatively close to thetransmitting node. Such a determination also may be made based on one ormore interference rules 530 that may define, for example, marginsrelating to an acceptable level of interference for a given transmissionrate, coding scheme, or other conditions. As an example, based on theRSSI of any received grants along with the receive margin information, anode may determine whether it should request an overlapping transmissionand, if so, how to select the transmit power to limit potentialinterference with any scheduled transmissions. If the interferencedeterminer 528 determines that a desired transmissions may undulyinterfere with receptions at one or more neighboring nodes, thetransmitting mode 500 may elect to, for example: abstain fromtransmitting the request to transmit, delay sending of a request totransmit, send a request that requests to transmit at a later time, senda request to transmit at a reduced power level, adjust a transmit timeperiod (e.g., TXOP), or take some other suitable action. For example, ifa transmitting node elects to transmit at a lower power level, it maystill want to send the same number of bits per packet. In this case, thetransmitting node may specify a longer TXOP.

Techniques such as those discussed above regarding whether to issue arequest to transmit data also may be used to determine whether totransmit via the control channel. For example, if a node uses arelatively excessive amount of power to transmit over the controlchannel, that node's transmission of control information may interferewith the reception of data at a neighboring node. In particular, thismay occur when the data transmitting node that is associated with thedata receiving node is further from the data receiving node than thenode that is transmitting over the control channel. Such interferencealso may occur when the frequencies associated with the transmission ofthe control information and the reception of data are relatively close.As an example of the latter, referring to FIG. 3 the frequency band ofthe portion of the data channel being used (e.g., sub-channel 306D) maybe relatively close in frequency to the frequency band of the portion ofthe control channel being used (e.g., sub-channel 304D). Operationsrelating to addressing the above near-far issue will be discussed inmore detail in conjunction with FIG. 10. In certain cases, a node'stransmission could desensitize a receiver in its immediate neighborhoodcausing saturation and loss of packets at the receiver (also known asreceiver jamming). This would happen even if the transmission isfrequency separated from the reception. Determination of whether totransmit on a control channel based on the likelihood of desensitizing areceiver in the neighborhood is also part of the transmit constraintsstate processing.

As represented by block 1002, a node that wishes to transmit over thecontrol channel will monitor the control channel for informationindicative of whether any neighboring receiving nodes have scheduled(e.g., granted) any requested transmissions. At block 1004 the node willthus define its state records (e.g., transmit constraints state) asdiscussed herein.

At block 1006, at some point in time the node may determine that itwishes to transmit over the control channel. In this case, the node mayutilize the transmit constraints state information as well astransmission parameters associated with the intended control channeltransmission to determine whether the desired transmission willinterfere with neighboring receptions or will desensitize a neighboringreceiver. This may involve, in a similar manner as discussed herein withother similar operations, determining whether and how to schedule thedesired transmission. For example, in some implementations a decisionmay be made to proceed with the transmission, delay the transmission, orchange some parameter associated with the transmission (block 1008).

In some implementations the transmit power to be used to transmit acontrol message may not be adjusted in an attempt to avoid interference.For example, in some cases it is desirable to ensure that controlmessages are transmitted with a certain power level to enable nodes thatreceive the control message to make interference avoidance decisionsbased on the received power level of the control message (e.g., asdiscussed herein). Thus, in these cases, interference avoidance mayinvolve adjusting the timing of the transmission or some other parameterthat does not affect the transmit power. In cases where interferenceavoidance may not be avoided by rescheduling the transmission of thecontrol channel messages (e.g., transmitting at a later time),interference between the control and data channels may be addressedthrough the use of the guard bands discussed above and/or increasedmargin.

At block 1010, once the node determines that it may transmit over thecontrol channel without causing undue interference with data receptionat neighboring nodes, the node may invoke the access scheme designatedfor the control channel. For example, to avoid latency on the controlchannel nodes may transmit on the control channel one at a time. Someimplementations may employ an interference avoidance scheme such ascarrier sense multiple access with collision avoidance (“CSMA/CA”). Inthis way, operation on the FDM control channel may be essentiallylimited only by the signal-to-noise ratio of the channel. In someimplementations no reservations or NAV settings are permitted since thenode that is transmitting on the data channel may not be able to listento the control channel to maintain NAV settings. Once the node gainsaccess to the control channel, the node may then transmit its controlmessage over the control channel as discussed herein (block 1012).

At block 710 in FIG. 7, in the event a decision is made to issue arequest to transmit, the control message generator 506 generates anappropriate request message 534 including, for example, requested startand end times or some other parameters discussed herein relating to thedesired transmission. The transmitter 520 then transmits the requestover the control channel.

Referring again to FIG. 8, the receiving node receives the request totransmit at block 808. At block 810 the receiving node determineswhether to schedule the requested transmission and, if so, how toschedule the transmission. As mentioned above, this decision may bebased on the parameters of the request and on the rate prediction state.

In the example of FIG. 6, a sustainable reception determiner 632 usesthe rate prediction state records 612 to determine whether it ispossible to maintain sustainable reception of data at the receiving node600 in view of any scheduled transmissions by nodes that are close tothe receiving node (e.g., by selecting different parameters). Forexample, the node may determine an anticipated level of interference,and thereby determine a sustainable rate for the schedule transmission,based on the RSSI of any received confirmation messages and the transmitpower delta information. In the event the anticipated interference isexcessive, the receiving node may simply not respond to the request totransmit. In this case, the transmitting node may back-off and attempt arequest at a later time.

A variety of factors may be taken into account when deciding whether toschedule an overlapping transmission. For example, such a decision maytake into account the signal strength of the most recent grant. Anadditional consideration may be whether the grant sender has recentlytransmitted a RUM indicating a relatively high degree of disadvantage.Also, the amount of data that needs to be sent may factor into thedecision as to whether to schedule an overlapping transmission. Forexample, if the amount of data to be sent is relatively small, the datamay be sent at low power and over a longer period of time to facilitatethe overlapping of transmissions.

In the event the receiving node elects to schedule the transmission, atransmission parameter definer component 634 may define one or moretransmission parameters 610 to facilitate effective reception of thescheduled transmission (e.g., select different parameters). For example,the transmission parameters 610 may include one or more of: transmissionstart time, transmission end time, transmission time period, timesegment definitions, transmission power, a quantity of redundancy bitsto transmit, receive margin, C/I, or code rate that may be used duringthe transmission or that may be used to define one or more transmissionparameters.

At block 812, the control message generator 606 generates a grantmessage 636 including information relating to, for example, the assignedTXOP period, designated bandwidth for the transmission, rate assignment,and any other grant-related parameter discussed herein. The transmitter620 then transmits the grant via the control channel.

At block 712 in FIG. 7, the receiver 518 (FIG. 5) receives the grant viathe control channel. As discussed above, the RSSI measurer 524 maymeasure signal strength or some other power-related parameter associatedwith the received grant message.

At block 714, the control message processor 504 extracts thetransmission parameter-related information from the grant message. Inaddition, a transmission parameter definer 536 may, as necessary,determine any transmission parameters that were not directly provided bythe grant. As discussed above the transmitting node 500 may maintain itstransmission parameters 510 in a data memory for subsequent use by thetransmission controller 514 and the control message generator 506.

At block 716, the control message generator 506 generates a confirmation538 (e.g., in response to the received grant). In general, thetransmission of the confirmation 538 immediately precedes thetransmission of the data over the data channel.

In some implementations the confirmation may include informationrelating to the scheduled transmission as discussed herein. For example,the confirmation 538 may include a transmission start time, atransmission end time, packet format and a sequence number informationas provided by, for example, a packet formatter 540, and transmit powerdelta information 542. The transmitter 520 transmits the confirmationmessage (e.g., in conjunction with the pilot signal) via the controlchannel.

As represented by block 814 in FIG. 8, the receiving node and any othernodes in the vicinity of the transmitting node receive the confirmation.Here, the other nodes may thus update their state information based onthe confirmation. For the associated receiving node the confirmationindicates the chosen transmission mode and the packet format (e.g., forHARQ). In some implementations the packet format indication may beprovided in-band (or implicitly) rather than explicitly in theconfirmation message.

In a typical implementation the grant issued at block 812 specifies thatthe transmitting node may commence its TXOP immediately after itreceives a grant. In some cases, however, the grant may indicate a laterstart time for the TXOP. In the event the TXOP starts at a later pointin time the transmitting and receiving nodes may commence the actualdata exchange by invoking an acknowledgement/confirmation exchange (notshown in FIGS. 7 and 8) to provide updated state information for thenodes.

As represented by block 718 of FIG. 7, the transmitting node 500transmits its data via the data channel during the scheduled TXOPperiod. Here, if the TXOP is not segmented the transmitting node 500transmits the data for the entire TXOP (block 720). Otherwise, asdiscussed below, the transmitting node transmits the data in segments.The transmitting node 500 transmits the data using the currenttransmission parameters 510 and the transmit power delta 542 todetermine the appropriate transmission times, transmission rate, coderate, and so on. The transmitted data is then received via the datachannel by the receiving node 600 as represented by block 816 of FIG. 8.If the TXOP is not segmented the receiving node 600 receives the datafor the entire TXOP (blocks 818 and 820). Otherwise, as discussed below,the receiving node receives the data in segments.

FIGS. 11 and 12 illustrate two examples of how a transmission may bescheduled in view of a scheduled transmission of a neighboring node. InFIG. 11, a node A issued a request (REQ-A) that was granted by a node B.The grant (GNT-B) from node B defined a start time and an end time forthe TXOP as represented by the lines 1102 and 1104, respectively. Upontransmission of a confirmation message (CNF-A), node A commencedtransmission of its data as represented by the shaded portion of FIG. 11associated with the data channel being used by node A.

At a later point in time, a node C issues a request (REQ-C) that wasgranted by a node D. In this case, node D elected to avoid any overlapwith the scheduled transmission for node A. As discussed herein, thiselection may be made based on a determination that the transmissionsfrom node A would unduly interfere with the reception of data at node D.Accordingly, the grant (GNT-D) from node D defined a start time and anend time for this TXOP as represented by the lines 1106 and 1108,respectively. Upon transmission of its confirmation message (CNF-C),node C commenced transmission of its data at the designated time asrepresented by the shaded portion of FIG. 11 associated with the datachannel being used by node C.

In FIG. 12, node A again issued a request (REQ-A) that was granted by anode B. This grant (GNT-B) from node B defined a start time and an endtime for the TXOP as represented by the lines 1202 and 1204,respectively. After transmitting its confirmation message (CNF-A), nodeA transmitted its data as represented by the shaded portion of FIG. 11associated with the data channel being used by node A.

Again, node C issues a request (REQ-C) that was granted by a node D. Inthis case, however, node D elected to overlap the transmission destinedfor node D with the scheduled transmission for node A. Here, the grant(GNT-D) from node D defined a start time and an end time for this TXOPas represented by the lines 1206 and 1208, respectively. Thus, asrepresented by the crosshatched portion of FIG. 11, the data channel maybe concurrently used by both nodes A and C. Here, it should beappreciated that this technique may serve to provide greater spatialreuse efficiency as compared to media access control schemes where atransmitter will only use a communication medium (e.g., a channel) whenthat medium is free of any other transmission.

Referring again to blocks 720 and 818 of FIGS. 7 and 8, respectively, insome implementations a given TXOP may define several transmit timesegments (e.g., time segments 424A and 424B in FIG. 4). In some cases atwo-way exchange employing acknowledgement and confirmation messages maybe used to maintain state and update transmission parameters, asnecessary, throughout the TXOP.

At blocks 722 and 724, after the transmitting node transmits a givensegment the node may monitor the control channel during at least aportion of the defined inter-segment time interval. For example, duringthis interval (e.g., interval 426 in FIG. 4) the transmitting node mayreceive an acknowledgement from the associated receiving node thatacknowledges receipt of the most recently transmitted segment. Inaddition, the transmitting node may receive other control informationduring this interval that may be used to update the state records (e.g.,transmit constraints state and rate prediction state) of that node asdiscussed herein. Also, the transmitting node may receive an indicationfrom the receiving node that the transmission may be terminated.

As represented by block 822 of FIG. 8, the receiving node receives eachsegment and decodes the corresponding data, as necessary. At block 824,in the event the receiving node has successfully decoded all of the datato be transmitted during a TXOP (e.g., an entire packet), the receivingnode may define control information to be sent to the transmitting nodethat indicates that the transmission is over. In the event the packetwas successfully decoded even though one or more segments remainscheduled to be transmitted, this control information may indicate, forexample, that the duration of the TXOP is to be adjusted (i.e.,decreased) or that that one or more upcoming time segments are to beeliminated (e.g., adjust the number of time segments in the TXOP).

As represented by block 826, the reception controller 614 of thetransmitting node 600 may determine whether to adjust one or moretransmission parameters for subsequent segments based on controlinformation that has been received since the time of the grant at block812 (e.g., based on the current rate predictions state). Here, thereception controller 614 may elect to adjust one or more transmissionparameters if another wireless node has recently scheduled atransmission that will take place at the same time as one or more of thesubsequent segments. Such an adjustment may involve, for example,reducing the transmission rate, changing the code rate, adjusting thetransmission times, or modifying some other parameter for one or more ofthe remaining segments.

It should be appreciated that due to the interference avoidancetechniques described herein, the received C/I associated with ongoingscheduled transmissions (TXOPs) may not change by significant amountduring the TXOP. For example, a request to transmit at the same time asanother scheduled transmission may not be scheduled (e.g., granted) ifit is determined that the requested transmission will unduly interferewith a previously scheduled transmission. Consequently, since a node mayassume that the conditions of the communication channel may not changeby a significant amount during a given TXOP period, a receiving node mayaggressively select transmission and coding rates for its scheduledtransmission.

As represented by block 830 the control message generator 606 may thengenerate an acknowledgement 638 that acknowledges receipt of a segment(e.g., segment 424A). Here, a different acknowledgement may be used toprovide feedback for each segment of an ongoing transmission. Inaddition, the acknowledgement 638 may include or be associated withsimilar information as was transmitted by or in conjunction with thegrant 636 at block 812, modified as necessary to include informationregarding one or more adjusted transmission parameters from block 826.In other words, the acknowledgement may act as an intermediate“remaining grant” that provides updated resource allocation and ratefeedback information and that may be used by neighboring nodes to updatetheir state regarding scheduled receptions in their vicinity.Accordingly, the acknowledgement 638 may comprise one or more of:transmission start time for at least one of the time segments,transmission end time for at least one of the time segments,transmission time period for at least one of the time segments,transmission power for at least one of the time segments, a quantity ofredundancy bits to transmit for at least one of the time segments, coderate for at least one of the time segments, expected channel tointerference ratio for at least one of the time segments, receivemargin, and a pilot signal.

Referring again to FIG. 7, at block 726 the transmission controller 514adjust its transmission parameters, as necessary, based on the controlinformation it receives during the inter-segment interval. As mentionedabove, this adjustment may be based on information received via anacknowledgement from the associated receiving node or based oninformation received from other neighboring nodes (e.g., grants or otheracknowledgements).

As represented by block 728, in some implementations the control messagegenerator 506 generates another form of confirmation message (e.g.,similar to the confirmation message transmitted at block 716) to informneighboring nodes of the transmission parameters that will be used forthe transmission during subsequent time segments (e.g., time segment424B) or that the transmission is completed. This confirmation messagemay thus include information that is similar to the information includedin the confirmation 538. In this case, however, the confirmationinformation may include appropriate adjustments based on any changedtransmission parameters and including the appropriate timing parametersthat relate to the remaining segments to be transmitted. Thus, theconfirmation transmitted at block 728 may comprise, for example,transmission start time for at least one of the time segments,transmission end time for at least one of the time segments,transmission time period for at least one of the time segments, transmitpower delta, packet format, and a pilot signal.

Referring back to FIG. 8, as represented by block 832, the receivingnode continues to monitor the control channel for control informationduring the inter-segment interval and when the receiving node ismonitoring the data channel for the transmitted segments. Accordingly,the receiving node will continue to update its state so that it maycontinue to adjust the transmission parameters for the current TXOP, asnecessary.

As represented by block 730 of FIG. 7 and block 826 of FIG. 8 the aboveoperations are repeated for each subsequently transmitted segment. Asrepresented by block 836 of FIG. 8, after all of the segments have beentransmitted (e.g., at the end of the TXOP period) the node comprisingthe receiving node 600 continues monitoring the control channel toupdate its transmit constraints state and rate prediction state and toprocess or initiate requests to transmit, as necessary.

Referring again to FIG. 7, at the end of TXOP period the transmittingmode monitors the control channel for a defined period of time so thatit may update or reacquire its state records based on received controlmessages such as grants, confirmations, acknowledgements, and RUMs(block 732). FIGS. 11 and 12 illustrate examples of such state updateperiods (i.e., post-TXOP monitor periods) that are defined followingeach scheduled transmission. Here, a state update for node A (STU-A) mayimmediately follow the termination of the TXOP for node A as representedby the lines 1104 and 1204. Similarly, a state update for node C (STU-C)may immediately follow the termination of the TXOP for node C asrepresented by the lines 1108 and 1208.

As mentioned above in conjunction with FIG. 4, the control information(e.g., message exchange messages and RUMs) received at this time mayinclude information that is scheduled for transmission either with orwithout regard to the TXOP period of the transmitting node 500. Twoexamples of the former case will be discussed in conjunction with FIG.13. FIG. 13A relates to a scenario where at the end of the TXOP period anode retransmits information that was previously transmitted when aneighboring node was transmitting data. FIG. 13B relates to a scenariowhere a node may intentionally delay transmitting its controlinformation until the end of the TXOP period of a neighboring node toensure that the information is received by the neighboring node.

Referring initially to FIG. 13A, as represented by block 1302 a givennode maintains its state by monitoring the control channel forinformation transmitted by other nodes as discussed herein. In this way,the node may acquire information regarding the scheduled TXOP periods ofits neighboring transmitting nodes.

As represented by block 1304 at some point in time (e.g., as discussedherein) the node may transmit control information via the controlchannel. In conjunction with this operation, the node may determinewhether any of its neighboring transmitting nodes are transmitting overthe data channel at the same time the node transmits its controlinformation over the control channel (block 1306). In this way, the nodemay determine that one or more neighboring nodes may not have receivedits control information.

Accordingly, at block 1308 the node may transmit another control messageafter the end of the TXOP period of each of its neighboring nodes thatwould not have received the initial control message. Here, the“retransmitted” control message may repeat the information that waspreviously transmitted in the initial control message. In this way, thenode may ensure that its neighboring nodes will take its scheduledtransmissions into account when those nodes determine whether to issue arequest to transmit or whether to grant a requested transmission.

Referring now to FIG. 13B, as represented by block 1312 a node maintainsits state by monitoring the control channel for information transmittedby other nodes. The node may thus acquire information regarding thescheduled TXOP periods of its neighboring transmitting nodes.

As represented by block 1314 at some point in time (e.g., as discussedherein) the node may determine that it needs to transmit controlinformation via the control channel. Before the node transmits thecontrol information, however, the node may determine whether any of itsneighboring transmitting nodes are scheduled to transmit over the datachannel at the same time that node intends to transmit its controlinformation over the control channel. In this case, the node (e.g., thetransmission controller 514 or the reception controller 614) mayschedule (e.g., delay) transmission of its control information so thatits neighboring nodes may receive the control information to betransmitted (block 1316).

As represented by block 1318, after the end of the TXOP period of eachof its neighboring nodes, the node transmits the delayed controlinformation. Again, the node may thereby ensure that its neighboringnodes will take its scheduled transmissions into account when thosenodes determine whether to issue a request to transmit or grant arequested transmission.

Referring again to FIG. 7, once the node including the transmitting node500 receives this control information, it updates or reacquires itsstate records for use in conjunction with the invocation of futurerequests to transmit or in conjunction with the granting of request totransmit from other nodes (block 734). As represented by block 736, thenode may then continue to monitor the control channel to update itsstate or service requests to transmit, or it may invoke additionalrequests to transmit any other backlogged data.

The control message exchange schemes described herein may be implementedin a variety of ways. For example, in some implementations differenttypes of messages may be given higher or a lower priority on the controlchannel. As an example, acknowledgement messages may be given priorityover request messages (using shorter IFS) since theacknowledgement-related exchange occurs in the middle of an ongoingTXOP. This prioritization scheme may avoid unnecessary waste of databandwidth during the TXOP.

In some implementations a RUM may be an unacknowledged broadcasttransmission. In addition, the RUM may be assigned the lowest accesspriority as compared to a request and an acknowledgement. Moreover, insome implementations an ongoing TXOP may not be terminated by a RUM.

In some implementations, fairness may be implemented over time scalescorresponding to a maximum length of a TXOP of some other amount oftime. For example, a disadvantaged node may specify that its RUM isvalid for a defined period of time (e.g., an amount of time that issufficient to schedule its own TXOP). In some implementations thisdefined period of time may be included in the RUM. Conversely, in someimplementations a node that receives a RUM may specify that any RUMS itreceives will be taken into consideration for a defined period of time.For example, such a node may define a window of time within which it maylimit its transmissions or requests for transmissions, if it hasreceived RUMS from a particular node. It should be appreciated that theabove defined periods of time may be dynamically changed depending uponcurrent conditions in the system.

In some implementations, if a transmitting node with backlogged data isunable to transmit requests due to the current transmit constraintsstate, the transmitting node may send an indication of its backloggedstatus to its associated receiving node (e.g., using a request messagewith a transmit constrained bit set). In this case, the receiving nodemay use the RUM mechanism to indicate to neighboring transmitting nodesthat they should back off their transmissions.

In some implementations overhead associated with the message exchangescheme may be reduced by eliminating the request and the grant. Forexample, for transmission of relatively short packets a transmitter mayinitiate a message exchange by simply transmitting a confirmation on thecontrol channel and then transmitting the data on the data channel,assuming such a transmission is permitted by the current transmitconstraints state. Here, the confirmation informs the neighboring nodesof the upcoming transmission. In general, the length of such a datapacket may be short. For example, in some embodiments the length of sucha data packet is shorter than the length of a given time segment (e.g.,time segment 424A). Here, since the C/I at the receiving node may not beknown, the transmitting node may select conservative values for one ormore of: transmit power, transmission rate, or coding rate.

After transmitting its data, the transmitting node will wait for anacknowledgement from the associated receiving node. In the event anacknowledgement is not received, the transmitting node may back off andretry the transmission using the abbreviatedconfirmation-acknowledgement exchange. Alternatively, the transmittingnode may back off and retry the transmission using the fullrequest-grant-confirmation exchange.

Alternatively, an unsolicited grant scheme may be employed whereby areceiving node transmits a grant any time that the current interferencesituation at the receiving node indicates that data may be reliablyreceived. In this case, a transmitting node that receives theunsolicited grant may select a transmit power in accordance with anyconstraints that may be imposed by the current transmit constraintsstate.

It should be appreciated that the operation and contents of controlmessages such as those described herein may depend on the type of devicethat issues the request. For example, an implementation where a pair ofassociated nodes comprising an access point and access terminal haveestablished a forward link (i.e., data flow from the access point to theaccess terminal), a request made by the access point may include one ormore parameters that may have been described above in conjunction withthe grant. For example, this request may comprise information regardingwhat the access point wants to send and how the access point wants tosend it including, for example, a designated TXOP period, an amount ofdata to be sent, frequency resources to be used such as designatedbandwidth, and so on. In this case, in response to the request theaccess terminal may simply transmit a message (e.g., a “grant”) thataccepts the request and includes information regarding, for example, asupported transmission rate to the access point, whereupon the accesspoint confirms receipt of this response. In this case, the responsegenerated by the access terminal may not, in a general sense, actually“grant” the request by the access point.

Various provisions also may be taken to address “near-far” problems. Asmentioned above, the near far problem may involve interference betweennodes (e.g., when a transmitting node is interfering with a receivingnode whose associated transmitting node is further away than interferingtransmitting node). An example of a solution for near-far problems dueto transmissions on the control channel was discussed above inconjunction with FIG. 10.

A reciprocal near-far problem relates to data transmitting nodes thatare interfering with another node's reception of control messages. Inother words, a node may become deaf to the control channel if there is astrong data transmitting node in the near vicinity. It should beappreciated however, that this problem is similar to the case where theaffected node itself is transmitting and, hence, is not receivingcontrol channel messages. Accordingly, the affected node may be able toupdate its state during the quiet post-TXOP monitor period of theinterfering transmitting node.

Similar techniques as described herein may be used to address near-farissues on the data channel. For example, when the data channel utilizesOFDMA there may be other data transmissions that result in leakageinterference that affects data reception at a receiving node. Theinterference management methods described herein relating to therequest-grant-confirmation exchange and the acknowledgement-confirmationexchange also may be applied to address this near far-problem forreception of data with overlapping OFDMA transmissions. Similar tointerference management thresholds applied to the transmit constraintsstate and the rate predictions state, these thresholds may be extendedfor OFDMA inter-hop-port interference. In addition, when a node (e.g.,an access point) schedules multiple simultaneous receptions, thesereceptions may be power controlled by the access point to manage thenear-far problem.

Various techniques may be employed for determining whether to issue orgrant a request as taught herein. For example, some implementations mayutilize one or more thresholds that are compared with one or more of theparameters described above. As a specific example, a determination ofwhether to schedule a transmission may be based on comparison of athreshold with a value that is based on an estimated channel gainassociated with at least one node and an anticipated transmit power forthe transmission being scheduled. Finally, it should be noted thatcertain control information between the transmitter and receiver that isnot pertinent to interference management may be sent along with data onthe data channel as opposed to the control channel. This ensures thatthe control channel is used as minimally as possible, since keeping itsutilization low is important due to the random access nature. As anexample, certain parameters of the confirm message, such as themodulation method used, number of bits of data being sent, remainingdata in the buffer, flow identifier (in the event multiple flows fromthe transmitter are being multiplexed) and in some cases even code ratecould be sent along with the data as in-band control.

The teachings herein may be incorporated into a device employing variouscomponents for communicating with at least one other wireless device.FIG. 14 depicts several sample components that may be employed tofacilitate communication between devices. Here, a first device 1402(e.g., an access terminal) and a second device 1404 (e.g., an accesspoint) are adapted to communicate via a wireless communication link 1406over a suitable medium.

Initially, components involved in sending information from the device1402 to the device 1404 (e.g., a reverse link) will be treated. Atransmit (“TX”) data processor 1408 receives traffic data (e.g., datapackets) from a data buffer 1410 or some other suitable component. Thetransmit data processor 1408 processes (e.g., encodes, interleaves, andsymbol maps) each data packet based on a selected coding and modulationscheme, and provides data symbols. In general, a data symbol is amodulation symbol for data, and a pilot symbol is a modulation symbolfor a pilot (which is known a priori). A modulator 1412 receives thedata symbols, pilot symbols, and possibly signaling for the reverselink, and performs modulation (e.g., OFDM or some other suitablemodulation) and/or other processing as specified by the system, andprovides a stream of output chips. A transmitter (“TMTR”) 1414 processes(e.g., converts to analog, filters, amplifies, and frequency upconverts)the output chip stream and generates a modulated signal, which is thentransmitted from an antenna 1416.

The modulated signals transmitted by the device 1402 (along with signalsfrom other devices in communication with the device 1404) are receivedby an antenna 1418 of the device 1404. A receiver (“RCVR”) 1420processes (e.g., conditions and digitizes) the received signal from theantenna 1418 and provides received samples. A demodulator (“DEMOD”) 1422processes (e.g., demodulates and detects) the received samples andprovides detected data symbols, which may be a noisy estimate of thedata symbols transmitted to the device 1404 by the other device(s). Areceive (“RX”) data processor 1424 processes (e.g., symbol demaps,deinterleaves, and decodes) the detected data symbols and providesdecoded data associated with each transmitting device (e.g., device1402).

Components involved in sending information from the device 1404 to thedevice 1402 (e.g., a forward link) will be now be treated. At the device1404, traffic data is processed by a transmit (“TX”) data processor 1426to generate data symbols. A modulator 1428 receives the data symbols,pilot symbols, and signaling for the forward link, performs modulation(e.g., OFDM or some other suitable modulation) and/or other pertinentprocessing, and provides an output chip stream, which is furtherconditioned by a transmitter (“TMTR”) 1430 and transmitted from theantenna 1418. In some implementations signaling for the forward link mayinclude power control commands and other information (e.g., relating toa communication channel) generated by a controller 1432 for all devices(e.g. terminals) transmitting on the reverse link to the device 1404.

At the device 1402, the modulated signal transmitted by the device 1404is received by the antenna 1416, conditioned and digitized by a receiver(“RCVR”) 1434, and processed by a demodulator (“DEMOD”) 1436 to obtaindetected data symbols. A receive (“RX”) data processor 1438 processesthe detected data symbols and provides decoded data for the device 1402and the forward link signaling. A controller 1440 receives power controlcommands and other information to control data transmission and tocontrol transmit power on the reverse link to the device 1404.

The controllers 1440 and 1432 direct various operations of the device1402 and the device 1404, respectively. For example, a controller maydetermine an appropriate filter, reporting information about the filter,and decode information using a filter. Data memories 1442 and 1444 maystore program codes and data used by the controllers 1440 and 1432,respectively.

FIG. 14 also illustrates that the communication components may includeone or more components that perform one or more of the operations astaught herein. For example, a media access control (“MAC”) component1446 may cooperate with the controller 1440 and/or other components ofthe device 1402 to send data and control information to and receive dataand control information from another device (e.g., device 1404) inaccordance with the asynchronous techniques as taught herein. Similarly,a MAC component 1448 may cooperate with the controller 1432 and/or othercomponents of the device 1404 to send data and control information toand receive data and control information from another device (e.g.,device 1402) in accordance with the described asynchronous techniques.

The teachings herein may be incorporated into (e.g., implemented withinor performed by) a variety of apparatuses (e.g., devices). For example,each node may be configured, or referred to, as an access point (“AP”),NodeB, Radio Network Controller (“RNC”), eNodeB, Base Station Controller(“BSC”), Base Transceiver Station (“BTS”), Base Station (“BS”),Transceiver Function (“TF”), Radio Router, Radio Transceiver, BasicService Set (“BSS”), Extended Service Set (“ESS”), Radio Base Station(“RBS”), or some other terminology. Certain nodes also may be referredto as subscriber stations. A subscriber station also may be known as asubscriber unit, a mobile station, a remote station, a remote terminal,an access terminal, a user terminal, a user agent, a user device, oruser equipment. In some implementations a subscriber station maycomprise a cellular telephone, a cordless telephone, a SessionInitiation Protocol (“SIP”) phone, a wireless local loop (“WLL”)station, a personal digital assistant (“PDA”), a handheld device havingwireless connection capability, or some other suitable processing deviceconnected to a wireless modem. Accordingly, one or more aspects taughtherein may be incorporated into a phone (e.g., a cellular phone or smartphone), a computer (e.g., a laptop), a portable communication device, aportable computing device (e.g., a personal data assistant), anentertainment device (e.g., a music or video device, or a satelliteradio), a global positioning system device, or any other suitable devicethat is configured to communicate via a wireless medium.

As mentioned above, in some aspects a wireless node may comprise anaccess device (e.g., a cellular or Wi-Fi access point) for acommunication system. Such an access device may provide, for example,connectivity for or to a network (e.g., a wide area network such as theInternet or a cellular network) via a wired or wireless communicationlink. Accordingly, the access device may enable another device (e.g., aWi-Fi station) to access the network or some other functionality.

A wireless node may thus include various components that performfunctions based on data transmitted or received by the wireless node.For example, an access point and an access terminal may include anantenna for transmitting and receiving signals (e.g., control and data).An access point also may include a traffic manager configured to managedata traffic flows that its receiver receives from a plurality ofwireless nodes or that its transmitter transmits to a plurality ofwireless nodes. In addition, an access terminal may include a userinterface configured to output an indication based on data received bythe receiver (e.g., based on a scheduled reception of data) or providedata to be transmitted by the transmitter.

A wireless device may communicate via one or more wireless communicationlinks that are based on or otherwise support any suitable wirelesscommunication technology. For example, in some aspects a wireless devicemay associate with a network or two or more wireless devices may form anetwork. In some aspects the network may comprise a local area networkor a wide area network. A wireless device may support or otherwise useone or more of a variety of wireless communication technologies,protocols, or standards such as, for example, CDMA, TDMA, OFDM, OFDMA,WiMAX, and Wi-Fi. Similarly, a wireless device may support or otherwiseuse one or more of a variety of corresponding modulation or multiplexingschemes. A wireless device may thus include appropriate components(e.g., air interfaces) to establish and communicate via one or morewireless communication links using the above or other wirelesscommunication technologies. For example, a wireless device may comprisea wireless transceiver with associated transmitter and receivercomponents (e.g., transmitters 520 and 620 and receivers 518 and 618)that may include various components (e.g., signal generators and signalprocessors) that facilitate communication over a wireless medium.

The components described herein may be implemented in a variety of ways.Referring to FIGS. 15-19, several apparatuses 1502, 1504, 1602, 1604,1702, 1704, 1802, 1804, and 1902 are represented as a series ofinterrelated functional blocks that may represent functions implementedby, for example, one or more integrated circuits (e.g., an ASIC) or maybe implemented in some other manner as taught herein. As discussedherein, an integrated circuit may include a processor, software, othercomponents, or some combination thereof.

The apparatuses 1502, 1504, 1602, 1604, 1702, 1704, 1802, 1804, and 1902may include one or more modules that may perform one or more of thefunctions described above with regard to various figures. For example,an ASIC for transmitting 1506, 1524, 1618, 1716, 1806, 1904, or 1908 maycorrespond to, for example, a transmitter as discussed herein. An ASICfor receiving 1522, 1606, 1620, 1706, 1820, 1906, 1914, or 1918, formonitoring 1508 or 1808, or for obtaining information 1622 or 1718 maycorrespond to, for example, a receiver as discussed herein. An ASIC fordefining state 1512, 1528, 1610, 1712, 1810, or 1916 may correspond to,for example, a state controller as discussed herein. An ASIC foradjusting transmission parameters 1510, for determining transmissionparameters 1530 or 1922, for defining control information 1526 or 1824,for defining information 1616 or 1714 may correspond to, for example, atransmission parameter definer as discussed herein. An ASIC for defininga time period 1516 or 1534 may correspond to, for example, atransmission parameter definer as discussed herein. An ASIC for issuinga request 1514 or 1912, for determining whether to issue a request 1518,for adjusting 1536, for determining whether to limit transmission 1612,for determining whether to abstain from sending a request 1814, fordetermining whether to transmit 1608, 1624, or 1910, or for determiningwhether to limit a request 1920 may correspond to, for example, atransmission controller as discussed herein. An ASIC for determininginterference 1520, 1614, or 1812 may correspond to, for example, aninterference determiner as discussed herein. An ASIC for scheduling1532, 1816, or 1822, or for determining a schedule 1708 may correspondto, for example, a transmission controller or a reception controller asdiscussed herein. An ASIC for determining sustainable reception 1624 or1710, or for determining whether to abstain from sending a grant 1818may correspond to, for example, a reception controller as discussedherein.

As noted above, in some aspects these components may be implemented viaappropriate processor components. These processor components may in someaspects be implemented, at least in part, using structure as taughtherein. In some aspects a processor may be adapted to implement aportion or all of the functionality of one or more of these components.In some aspects one or more of the components represented by dashedboxes are optional.

As noted above, the apparatuses 1502, 1504, 1602, 1604, 1702, 1704,1802, 1804, and 1902 may comprise one or more integrated circuits. Forexample, in some aspects a single integrated circuit may implement thefunctionality of one or more of the illustrated components, while inother aspects more than one integrated circuit may implement thefunctionality of one or more of the illustrated components.

In addition, the components and functions represented by FIGS. 15-19, aswell as other components and functions described herein, may beimplemented using any suitable means. Such means also may beimplemented, at least in part, using corresponding structure as taughtherein. For example, the components described above in conjunction withthe “ASIC for” components of FIGS. 15-19 also may correspond tosimilarly designated “means for” functionality. Thus, in some aspectsone or more of such means may be implemented using one or more processorcomponents, integrated circuits, or other suitable structure as taughtherein.

Also, it should be understood that any reference to an element hereinusing a designation such as “first,” “second,” and so forth does notgenerally limit the quantity or order of those elements. Rather, thesedesignations are used herein as a convenient method of distinguishingbetween two or more different nodes. Thus, a reference to first andsecond nodes does not mean that only two nodes may be employed there orthat the first node must precede the second node in some manner.

Those of skill in the art would understand that information and signalsmay be represented using any of a variety of different technologies andtechniques. For example, data, instructions, commands, information,signals, bits, symbols, and chips that may be referenced throughout theabove description may be represented by voltages, currents,electromagnetic waves, magnetic fields or particles, optical fields orparticles, or any combination thereof.

Those of skill would further appreciate that any of the variousillustrative logical blocks, modules, processors, means, circuits, andalgorithm steps described in connection with the aspects disclosedherein may be implemented as electronic hardware (e.g., a digitalimplementation, an analog implementation, or a combination of the two,which may be designed using source coding or some other technique),various forms of program or design code incorporating instructions(which may be referred to herein, for convenience, as “software” or a“software module”), or combinations of both. To clearly illustrate thisinterchangeability of hardware and software, various illustrativecomponents, blocks, modules, circuits, and steps have been describedabove generally in terms of their functionality. Whether suchfunctionality is implemented as hardware or software depends upon theparticular application and design constraints imposed on the overallsystem. Skilled artisans may implement the described functionality invarying ways for each particular application, but such implementationdecisions should not be interpreted as causing a departure from thescope of the present disclosure.

The various illustrative logical blocks, modules, and circuits describedin connection with the aspects disclosed herein may be implementedwithin or performed by an integrated circuit (“IC”), an access terminal,or an access point. The IC may comprise a general purpose processor, adigital signal processor (DSP), an application specific integratedcircuit (ASIC), a field programmable gate array (FPGA) or otherprogrammable logic device, discrete gate or transistor logic, discretehardware components, electrical components, optical components,mechanical components, or any combination thereof designed to performthe functions described herein, and may execute codes or instructionsthat reside within the IC, outside of the IC, or both. A general purposeprocessor may be a microprocessor, but in the alternative, the processormay be any conventional processor, controller, microcontroller, or statemachine. A processor may also be implemented as a combination ofcomputing devices, e.g., a combination of a DSP and a microprocessor, aplurality of microprocessors, one or more microprocessors in conjunctionwith a DSP core, or any other such configuration.

It is understood that any specific order or hierarchy of steps in anydisclosed process is an example of a sample approach. Based upon designpreferences, it is understood that the specific order or hierarchy ofsteps in the processes may be rearranged while remaining within thescope of the present disclosure. The accompanying method claims presentelements of the various steps in a sample order, and are not meant to belimited to the specific order or hierarchy presented.

The steps of a method or algorithm described in connection with theaspects disclosed herein may be embodied directly in hardware, in asoftware module executed by a processor, or in a combination of the two.A software module (e.g., including executable instructions and relateddata) and other data may reside in a data memory such as RAM memory,flash memory, ROM memory, EPROM memory, EEPROM memory, registers, a harddisk, a removable disk, a CD-ROM, or any other form of computer-readablestorage medium known in the art. A sample storage medium may be coupledto a machine such as, for example, a computer/processor (which may bereferred to herein, for convenience, as a “processor”) such theprocessor can read information (e.g., code) from and write informationto the storage medium. A sample storage medium may be integral to theprocessor. The processor and the storage medium may reside in an ASIC.The ASIC may reside in user equipment. In the alternative, the processorand the storage medium may reside as discrete components in userequipment. Moreover, in some aspects any suitable computer-programproduct may comprise a computer-readable medium comprising codes (e.g.,executable by at least one computer) relating to one or more of theaspects of the disclosure. In some aspects a computer program productmay comprise packaging materials.

The previous description of the disclosed aspects is provided to enableany person skilled in the art to make or use the present disclosure.Various modifications to these aspects will be readily apparent to thoseskilled in the art, and the generic principles defined herein may beapplied to other aspects without departing from the scope of thedisclosure. Thus, the present disclosure is not intended to be limitedto the aspects shown herein but is to be accorded the widest scopeconsistent with the principles and novel features disclosed herein.

1. A method of wireless communication, comprising: receiving, at a firstwireless node, information that indicates a scheduled reception of datafor a second wireless node; and determining, based on the receivedinformation, whether to transmit from the first wireless node during atime period associated with the scheduled reception of data.
 2. Themethod of claim 1, wherein the determination of whether to transmitcomprises determining whether to transmit via a control channel.
 3. Themethod of claim 2, further comprising: defining a transmit constraintsstate based on the received information; and determining, based on thetransmit constraints state, whether transmission by the first wirelessnode would interfere with reception at the second wireless node duringthe time period; wherein the determination of whether to transmit overthe control channel is based on the interference determination.
 4. Themethod of claim 3, wherein the transmit constraints state comprises atleast one of the group consisting of: transmission start time,transmission end time, transmission time period, receive margin, and areceived signal strength indication associated with a grant message oran acknowledgement message.
 5. The method of claim 2, wherein: the firstwireless node transmits data via a data channel; the control channel andthe data channel are frequency division multiplexed within a commonfrequency band; and the control channel is associated with a pluralityof sub-frequency bands that are interspersed within the common frequencyband.
 6. The method of claim 1, wherein the determination of whether totransmit comprises: determining, based on the received information,whether transmission by the first wireless node would interfere withreception at the second wireless node during the time period; anddetermining, based on the interference determination, whether or how toissue a request to transmit.
 7. The method of claim 6, wherein thedetermination of whether or how to issue a request to transmit comprisesat least one of the group consisting of: abstaining from sending arequest to transmit, requesting to transmit at a later time, delayingsending of a request to transmit, determining a transmit time period,and requesting to transmit at a reduced power level.
 8. The method ofclaim 1, further comprising: defining a transmit constraints state basedon the received information; determining, based on the transmitconstraints state, whether transmission by the first wireless node wouldinterfere with reception at the second wireless node during the timeperiod; and determining, based on the interference determination,whether or how to issue a request to transmit.
 9. The method of claim 8,wherein the transmit constraints state comprises at least one of thegroup consisting of: transmission start time, transmission end time,transmission time period, receive margin, and a received signal strengthindication associated with a grant message or an acknowledgementmessage.
 10. The method of claim 8, wherein the determination of whetherthe transmission would interfere with reception is based on a receivedsignal strength indication associated with a received grant message or areceived acknowledgement message.
 11. The method of claim 1, wherein:the received information comprises a grant message generated by thesecond wireless node in response to a request to transmit by a thirdwireless node; and the grant message comprises at least one of the groupconsisting of: transmission start time, transmission end time,transmission time period, transmission power, a quantity of redundancybits to transmit, code rate, expected channel to interference ratio,receive margin, and a pilot signal.
 12. The method of claim 1, wherein:the second wireless node receives data transmitted by a third wirelessnode during a plurality of time segments defined within a scheduledtransmit time period; and a time interval for transmission or receptionof control information is temporally located between the time segments.13. The method of claim 12, wherein: the received information comprisesat least one acknowledgement message that the second wireless nodetransmitted during the time interval; and the acknowledgement messagecomprises at least one of the group consisting of: transmission starttime for at least one of the time segments, transmission end time for atleast one of the time segments, transmission time period for at leastone of the time segments, transmission power for at least one of thetime segments, a quantity of redundancy bits to transmit for at leastone of the time segments, code rate for at least one of the timesegments, expected channel to interference ratio for at least one of thetime segments, receive margin, and a pilot signal.
 14. The method ofclaim 1, further comprising: monitoring for control information during adefined period of time following the time period; and defining, based onreceived control information, at least one of the group consisting of:transmit constraints state and rate prediction state.
 15. The method ofclaim 1, further comprising: receiving a resource utilization messagecomprising at least one of the group consisting of: a level of desiredinterference reduction, a resource to be cleared, and an indication of adegree to which reception at a receiving wireless node is not meeting adesired level of quality of service; and determining, based on theresource utilization message, whether to limit transmission by the firstwireless node.
 16. The method of claim 15, wherein the determination ofwhether to limit transmission comprises at least one of the groupconsisting of: abstaining from sending a request to transmit, requestingto transmit at a later time, delaying a request to transmit, determininga transmit time period, and requesting to transmit at a reduced powerlevel.
 17. The method of claim 15, further comprising performing, inresponse to a received resource utilization message, at least one of thegroup consisting of: changing a rate at which it transmits requestmessages, abstaining from transmitting request messages until a resourceutilization message of an associated receiver indicates a higher degreeof disadvantage than the received resource utilization message, changinga length of a scheduled transmit time period, changing a transmit powerdelta, and modifying a set of rules relating to a degree to whichtransmission by the first wireless node may interfere with reception atthe second wireless node.
 18. An apparatus for wireless communication,comprising: a receiver configured to receive, at a first wireless node,information that indicates a scheduled reception of data for a secondwireless node; and a transmission controller configured to determine,based on the received information, whether to transmit from the firstwireless node during a time period associated with the scheduledreception of data.
 19. The apparatus of claim 18, wherein thedetermination of whether to transmit comprises determining whether totransmit via a control channel.
 20. The apparatus of claim 19, furthercomprising: a state controller configured to define a transmitconstraints state based on the received information; and an interferencedeterminer configured to determine, based on the transmit constraintsstate, whether transmission by the first wireless node would interferewith reception at the second wireless node during the time period;wherein the determination of whether to transmit over the controlchannel is based on the interference determination.
 21. The apparatus ofclaim 20, wherein the transmit constraints state comprises at least oneof the group consisting of: transmission start time, transmission endtime, transmission time period, receive margin, and a received signalstrength indication associated with a grant message or anacknowledgement message.
 22. The apparatus of claim 19, wherein: thefirst wireless node transmits data via a data channel; the controlchannel and the data channel are frequency division multiplexed within acommon frequency band; and the control channel is associated with aplurality of sub-frequency bands that are interspersed within the commonfrequency band.
 23. The apparatus of claim 18, wherein the determinationof whether to transmit comprises: determining, based on the receivedinformation, whether transmission by the first wireless node wouldinterfere with reception at the second wireless node during the timeperiod; and determining, based on the interference determination,whether or how to issue a request to transmit.
 24. The apparatus ofclaim 23, wherein the determination of whether or how to issue a requestto transmit comprises at least one of the group consisting of:abstaining from sending a request to transmit, requesting to transmit ata later time, delaying sending of a request to transmit, determining atransmit time period, and requesting to transmit at a reduced powerlevel.
 25. The apparatus of claim 18, further comprising: a statecontroller configured to define a transmit constraints state based onthe received information; and an interference determiner configured todetermine, based on the transmit constraints state, whether transmissionby the first wireless node would interfere with reception at the secondwireless node during the time period; wherein the transmissioncontroller is further configured to determine, based on the interferencedetermination, whether or how to issue a request to transmit.
 26. Theapparatus of claim 25, wherein the transmit constraints state comprisesat least one of the group consisting of: transmission start time,transmission end time, transmission time period, receive margin, and areceived signal strength indication associated with a grant message oran acknowledgement message.
 27. The apparatus of claim 25, wherein thedetermination of whether the transmission would interfere with receptionis based on a received signal strength indication associated with areceived grant message or a received acknowledgement message.
 28. Theapparatus of claim 18, wherein: the received information comprises agrant message generated by a third wireless node in response to arequest to transmit; and the grant message comprises at least one of thegroup consisting of: transmission start time, transmission end time,transmission time period, transmission power, a quantity of redundancybits to transmit, code rate, expected channel to interference ratio,receive margin, and a pilot signal.
 29. The apparatus of claim 18,wherein: the second wireless node receives data transmitted by a thirdwireless node during a plurality of time segments defined within ascheduled transmit time period; and a time interval for transmission orreception of control information is temporally located between the timesegments.
 30. The apparatus of claim 29, wherein: the receivedinformation comprises at least one acknowledgement message that thesecond wireless node transmitted during the time interval; and theacknowledgement message comprises at least one of the group consistingof: transmission start time for at least one of the time segments,transmission end time for at least one of the time segments,transmission time period for at least one of the time segments,transmission power for at least one of the time segments, a quantity ofredundancy bits to transmit for at least one of the time segments, coderate for at least one of the time segments, expected channel tointerference ratio for at least one of the time segments, receivemargin, and a pilot signal.
 31. The apparatus of claim 18, wherein: thereceiver is further configured to monitor for control information duringa defined period of time following the time period; and the apparatusfurther comprises a state controller configured to define, based onreceived control information, at least one of the group consisting of:transmit constraints state and rate prediction state.
 32. The apparatusof claim 18, wherein: the receiver is further configured to receive aresource utilization message comprising at least one of the groupconsisting of: a level of desired interference reduction, a resource tobe cleared, and an indication of a degree to which reception at areceiving wireless node is not meeting a desired level of quality ofservice; and the apparatus further comprises a resource utilizationmessage processor configured to determine, based on the resourceutilization message, whether to limit transmission by the first wirelessnode.
 33. The apparatus of claim 32, wherein the determination ofwhether to limit transmission comprises at least one of the groupconsisting of: abstaining from sending a request to transmit, requestingto transmit at a later time, delaying a request to transmit, determininga transmit time period, and requesting to transmit at a reduced powerlevel.
 34. The apparatus of claim 32, wherein in response to a receivedresource utilization message the transmission controller performs atleast one of the group consisting of: changing a rate at which ittransmits request messages, abstaining from transmitting requestmessages until a resource utilization message of an associated receiverindicates a higher degree of disadvantage than the received resourceutilization message, changing a length of a scheduled transmit timeperiod, changing a transmit power delta, and modifying a set of rulesrelating to a degree to which transmission by the first wireless nodemay interfere with reception at the second wireless node.
 35. Anapparatus for wireless communication, comprising: means for receiving,at a first wireless node, information that indicates a scheduledreception of data for a second wireless node; and means for determining,based on the received information, whether to transmit from the firstwireless node during a time period associated with the scheduledreception of data.
 36. The apparatus of claim 35, wherein thedetermination of whether to transmit comprises determining whether totransmit via a control channel.
 37. The apparatus of claim 36, furthercomprising: means for defining a transmit constraints state based on thereceived information; and means for determining, based on the transmitconstraints state, whether transmission by the first wireless node wouldinterfere with reception at the second wireless node during the timeperiod; wherein the determination of whether to transmit over thecontrol channel is based on the interference determination.
 38. Theapparatus of claim 37, wherein the transmit constraints state comprisesat least one of the group consisting of: transmission start time,transmission end time, transmission time period, receive margin, and areceived signal strength indication associated with a grant message oran acknowledgement message.
 39. The apparatus of claim 36, wherein: thefirst wireless node transmits data via a data channel; the controlchannel and the data channel are frequency division multiplexed within acommon frequency band; and the control channel is associated with aplurality of sub-frequency bands that are interspersed within the commonfrequency band.
 40. The apparatus of claim 35, wherein the determinationof whether to transmit comprises: determining, based on the receivedinformation, whether transmission by the first wireless node wouldinterfere with reception at the second wireless node during the timeperiod; and determining, based on the interference determination,whether or how to issue a request to transmit.
 41. The apparatus ofclaim 40, wherein the determination of whether or how to issue a requestto transmit comprises at least one of the group consisting of:abstaining from sending a request to transmit, requesting to transmit ata later time, delaying sending of a request to transmit, determining atransmit time period, and requesting to transmit at a reduced powerlevel.
 42. The apparatus of claim 35, further comprising: means fordefining a transmit constraints state based on the received information;and means for determining, based on the transmit constraints state,whether transmission by the first wireless node would interfere withreception at the second wireless node during the time period; whereinthe means for determining whether to transmit determines, based on theinterference determination, whether or how to issue a request totransmit.
 43. The apparatus of claim 42, wherein the transmitconstraints state comprises at least one of the group consisting of:transmission start time, transmission end time, transmission timeperiod, receive margin, and a received signal strength indicationassociated with a grant message or an acknowledgement message.
 44. Theapparatus of claim 42, wherein the determination of whether thetransmission would interfere with reception is based on a receivedsignal strength indication associated with a received grant message or areceived acknowledgement message.
 45. The apparatus of claim 35,wherein: the received information comprises a grant message generated bya third wireless node in response to a request to transmit; and thegrant message comprises at least one of the group consisting of:transmission start time, transmission end time, transmission timeperiod, transmission power, a quantity of redundancy bits to transmit,code rate, expected channel to interference ratio, receive margin, and apilot signal.
 46. The apparatus of claim 35, wherein: the secondwireless node receives data transmitted by a third wireless node duringa plurality of time segments defined within a scheduled transmit timeperiod; and a time interval for transmission or reception of controlinformation is temporally located between the time segments.
 47. Theapparatus of claim 46, wherein: the received information comprises atleast one acknowledgement message that the second wireless nodetransmitted during the time interval; and the acknowledgement messagecomprises at least one of the group consisting of: transmission starttime for at least one of the time segments, transmission end time for atleast one of the time segments, transmission time period for at leastone of the time segments, transmission power for at least one of thetime segments, a quantity of redundancy bits to transmit for at leastone of the time segments, code rate for at least one of the timesegments, expected channel to interference ratio for at least one of thetime segments, receive margin, and a pilot signal.
 48. The apparatus ofclaim 35, wherein: the means for receiving monitors for controlinformation during a defined period of time following the time period;and the apparatus further comprises means for defining, based onreceived control information, at least one of the group consisting of:transmit constraints state and rate prediction state.
 49. The apparatusof claim 35, wherein: the means for receiving further receives aresource utilization message comprising at least one of the groupconsisting of: a level of desired interference reduction, a resource tobe cleared, and an indication of a degree to which reception at areceiving wireless node is not meeting a desired level of quality ofservice; and the apparatus further comprises means for determining,based on the resource utilization message, whether to limit transmissionby the first wireless node.
 50. The apparatus of claim 49, wherein thedetermination of whether to limit transmission comprises at least one ofthe group consisting of: abstaining from sending a request to transmit,requesting to transmit at a later time, delaying a request to transmit,determining a transmit time period, and requesting to transmit at areduced power level.
 51. The apparatus of claim 49, wherein in responseto a received resource utilization message the means for determiningwhether to transmit performs at least one of the group consisting of:changing a rate at which it transmits request messages, abstaining fromtransmitting request messages until a resource utilization message of anassociated receiver indicates a higher degree of disadvantage than thereceived resource utilization message, changing a length of a scheduledtransmit time period, changing a transmit power delta, and modifying aset of rules relating to a degree to which transmission by the firstwireless node may interfere with reception at the second wireless node.52. A computer-program product for wireless communication, comprising:computer-readable medium comprising codes executable by at least onecomputer to: receive, at a first wireless node, information thatindicates a scheduled reception of data for a second wireless node; anddetermine, based on the received information, whether to transmit fromthe first wireless node during a time period associated with thescheduled reception of data.
 53. An access point for wirelesscommunication, comprising: an antenna; a receiver configured to receive,at a first wireless node and via the antenna, information that indicatesa scheduled reception of data for a second wireless node; and atransmission determiner configured to determine, based on the receivedinformation, whether to transmit from the first wireless node and viathe antenna during a time period associated with the scheduled receptionof data.
 54. An access terminal for wireless communication, comprising:a receiver configured to receive, at a first wireless node, informationthat indicates a scheduled reception of data for a second wireless node;and a transmission determiner configured to determine, based on thereceived information, whether to transmit from the first wireless nodeduring a time period associated with the scheduled reception of data;and a user interface configured to output an indication based on datareceived by the receiver.
 55. A method of wireless communication,comprising: defining information that indicates a scheduled reception ofdata for a first wireless node, wherein the information is defined toenable a second wireless node to determine whether to transmit during atime period associated with the scheduled reception of data; andtransmitting the defined information.
 56. The method of claim 55,wherein the defined information comprises a grant message generated inresponse to a request to transmit generated by a third wireless node.57. The method of claim 56, wherein the grant message comprises at leastone of the group consisting of: transmission start time, transmissionend time, transmission time period, transmission power, a quantity ofredundancy bits to transmit, code rate, expected channel to interferenceratio, receive margin, and a pilot signal.
 58. The method of claim 55,further comprising: receiving data during a plurality of time segmentsdefined within a scheduled transmit time period; wherein a time intervalfor transmission of control information is temporally located betweenthe time segments.
 59. The method of claim 58, wherein the definedinformation comprises at least one acknowledgement message that istransmitted during the time interval.
 60. The method of claim 59,wherein the at least one acknowledgement message comprises at least oneof the group consisting of: transmission start time for at least one ofthe time segments, transmission end time for at least one of the timesegments, transmission time period for at least one of the timesegments, transmission power for at least one of the time segments, aquantity of redundancy bits to transmit for at least one of the timesegments, code rate for at least one of the time segments, expectedchannel to interference ratio for at least one of the time segments,receive margin, and a pilot signal.
 61. The method of claim 55, wherein:the first wireless node transmits data via a data channel; the definedinformation is transmitted via a control channel; the control channeland the data channel are frequency division multiplexed within a commonfrequency band; and the control channel is associated with a pluralityof sub-frequency bands that are interspersed within the common frequencyband.
 62. The method of claim 55, further comprising: determiningwhether the first wireless node will be able to receive data in asustainable manner when a third wireless node is transmitting; anddetermining, based on the sustainable reception determination, whetherto transmit the defined information.
 63. The method of claim 62, whereinthe sustainable reception determination is based on a rate predictionstate.
 64. The method of claim 63, wherein the rate prediction statecomprises at least one of the group consisting of: transmission starttime, transmission end time, transmission time period, transmit powerdelta, and a received signal strength indication associated with aconfirmation message.
 65. The method of claim 55, further comprising:determining whether the first wireless node will be able to receive datain a sustainable manner when a third wireless node is transmitting; andbased on the sustainable reception determination, defining theinformation to include at least one of the group consisting of: adifferent schedule, a different transmit time period, a differenttransmit power, a different quantity of redundancy bits to transmit, anda different code rate.
 66. The method of claim 55, further comprising:obtaining information relating to a scheduled transmit time period ofthe second wireless node; and scheduling transmission of the definedinformation based on the obtained information.
 67. The method of claim66, wherein the transmission of the defined information is scheduled tocommence after the scheduled transmit time period.
 68. An apparatus forwireless communication, comprising: a reception controller configured todefine information that indicates a scheduled reception of data for afirst wireless node, wherein the information is defined to enable asecond wireless node to determine whether to transmit during a timeperiod associated with the scheduled reception of data; and atransmitter configured to transmit the defined information.
 69. Theapparatus of claim 68, wherein the defined information comprises a grantmessage generated in response to a request to transmit generated by athird wireless node.
 70. The apparatus of claim 69, wherein the grantmessage comprises at least one of the group consisting of: transmissionstart time, transmission end time, transmission time period,transmission power, a quantity of redundancy bits to transmit, coderate, expected channel to interference ratio, receive margin, and apilot signal.
 71. The apparatus of claim 68, further comprising: areceiver configured to receive data during a plurality of time segmentsdefined within a scheduled transmit time period; wherein a time intervalfor transmission of control information is temporally located betweenthe time segments.
 72. The apparatus of claim 71, wherein the definedinformation comprises at least one acknowledgement message that istransmitted during the time interval.
 73. The apparatus of claim 72,wherein the at least one acknowledgement message comprises at least oneof the group consisting of: transmission start time for at least one ofthe time segments, transmission end time for at least one of the timesegments, transmission time period for at least one of the timesegments, transmission power for at least one of the time segments, aquantity of redundancy bits to transmit for at least one of the timesegments, code rate for at least one of the time segments, expectedchannel to interference ratio for at least one of the time segments,receive margin, and a pilot signal.
 74. The apparatus of claim 68,wherein: the first wireless node transmits data via a data channel; thedefined information is transmitted via a control channel; the controlchannel and the data channel are frequency division multiplexed within acommon frequency band; and the control channel is associated with aplurality of sub-frequency bands that are interspersed within the commonfrequency band.
 75. The apparatus of claim 68, further comprising: asustainable reception determiner configured to determine whether thefirst wireless node will be able to receive data in a sustainable mannerwhen a third wireless node is transmitting; and a reception controllerconfigured to determine, based on the sustainable receptiondetermination, whether to transmit the defined information.
 76. Theapparatus of claim 75, wherein the sustainable reception determinationis based on a rate prediction state.
 77. The apparatus of claim 76,wherein the rate prediction state comprises at least one of the groupconsisting of: transmission start time, transmission end time,transmission time period, transmit power delta, and a received signalstrength indication associated with a confirmation message.
 78. Theapparatus of claim 68, wherein: the apparatus further comprises asustainable reception determiner configured to determine whether thefirst wireless node will be able to receive data in a sustainable mannerwhen a third wireless node is transmitting; and based on the sustainablereception determination, the reception controller is further configuredto define the information to include at least one of the groupconsisting of: a different schedule, a different transmit time period, adifferent transmit power, a different quantity of redundancy bits totransmit, and a different code rate.
 79. The apparatus of claim 68,wherein: the apparatus further comprises a receiver configured to obtaininformation relating to a scheduled transmit time period of the secondwireless node; and the reception controller is further configured toschedule transmission of the defined information based on the obtainedinformation.
 80. The apparatus of claim 79, wherein the transmission ofthe defined information is scheduled to commence after the scheduledtransmit time period.
 81. An apparatus for wireless communication,comprising: means for defining information that indicates a scheduledreception of data for a first wireless node, wherein the information isdefined to enable a second wireless node to determine whether totransmit during a time period associated with the scheduled reception ofdata; and means for transmitting the defined information.
 82. Theapparatus of claim 81, wherein the defined information comprises a grantmessage generated in response to a request to transmit generated by athird wireless node.
 83. The apparatus of claim 82, wherein the grantmessage comprises at least one of the group consisting of: transmissionstart time, transmission end time, transmission time period,transmission power, a quantity of redundancy bits to transmit, coderate, expected channel to interference ratio, receive margin, and apilot signal.
 84. The apparatus of claim 81, further comprising: meansfor receiving data during a plurality of time segments defined within ascheduled transmit time period; wherein a time interval for transmissionof control information is temporally located between the time segments.85. The apparatus of claim 84, wherein the defined information comprisesat least one acknowledgement message that is transmitted during the timeinterval.
 86. The apparatus of claim 85, wherein the at least oneacknowledgement message comprises at least one of the group consistingof: transmission start time for at least one of the time segments,transmission end time for at least one of the time segments,transmission time period for at least one of the time segments,transmission power for at least one of the time segments, a quantity ofredundancy bits to transmit for at least one of the time segments, coderate for at least one of the time segments, expected channel tointerference ratio for at least one of the time segments, receivemargin, and a pilot signal.
 87. The apparatus of claim 81, wherein: thefirst wireless node transmits data via a data channel; the definedinformation is transmitted via a control channel; the control channeland the data channel are frequency division multiplexed within a commonfrequency band; and the control channel is associated with a pluralityof sub-frequency bands that are interspersed within the common frequencyband.
 88. The apparatus of claim 81, further comprising: means fordetermining whether the first wireless node will be able to receive datain a sustainable manner when a third wireless node is transmitting; andmeans for determining, based on the sustainable reception determination,whether to transmit the defined information.
 89. The apparatus of claim88, wherein the sustainable reception determination is based on a rateprediction state.
 90. The apparatus of claim 89, wherein the rateprediction state comprises at least one of the group consisting of:transmission start time, transmission end time, transmission timeperiod, transmit power delta, and a received signal strength indicationassociated with a confirmation message.
 91. The apparatus of claim 81,wherein: the apparatus further comprises means for determining whetherthe first wireless node will be able to receive data in a sustainablemanner when a third wireless node is transmitting; and based on thesustainable reception determination, the means for defining furtherdefines the information to include at least one of the group consistingof: a different schedule, a different transmit time period, a differenttransmit power, a different quantity of redundancy bits to transmit, anda different code rate.
 92. The apparatus of claim 81, wherein: theapparatus further comprises means for obtaining information relating toa scheduled transmit time period of the second wireless node; and themeans for defining schedules transmission of the defined informationbased on the obtained information.
 93. The apparatus of claim 92,wherein the transmission of the defined information is scheduled tocommence after the scheduled transmit time period.
 94. Acomputer-program product for wireless communication, comprising:computer-readable medium comprising codes executable by at least onecomputer to: define information that indicates a scheduled reception ofdata for a first wireless node, wherein the information is defined toenable a second wireless node to determine whether to transmit during atime period associated with the scheduled reception of data; andtransmit the defined information.
 95. An access point for wirelesscommunication, comprising: an antenna; an information definer configuredto define information that indicates a scheduled reception of data for afirst wireless node via the antenna, wherein the information is definedto enable a second wireless node to determine whether to transmit duringa time period associated with the scheduled reception of data; and atransmitter configured to transmit the defined information via theantenna.
 96. An access terminal for wireless communication, comprising:an information definer configured to define information that indicates ascheduled reception of data for a first wireless node, wherein theinformation is defined to enable a second wireless node to determinewhether to transmit during a time period associated with the scheduledreception of data; a transmitter configured to transmit the definedinformation; and a user interface configured to output an indicationbased on the scheduled reception of data.